"Multi-Classing" as Warlock/Cleric is definitely not optimal, as they will split their resources between Charisma and Wisdom, but whether or not it's 
dumb" depends on the particular build. Hexblade is frequently used as a 1 level dip for melee builds. However, since you're not really built for melee, it won't benefit you nearly as much. Going into Warlock, you gain access to the best Cantrip Damage spell, Eldritch Blast. If you take one more level, or take the Eldritch Adept feat, you can gain access to the invocation Agonizing Blast, which will allow you scale in damage similar to a ranger or fighter.

With your high Charisma, you might have been better off choosing Sorcerer with the Divine Soul origin to tie the Cleric spell list with your attribute strengths. (Look up "SorLock" guides for similar builds.)

As built, your character is vulnerable to Grappling and Dexterity Saves, which means you could be in trouble in both melee and against AOE spells. (Web, for example, will cause you lots of problems.)

That said, you shouldn't have any issues with healing at your current level. You have access to Cure Wounds and Healing Word (Great for reviving fallen party members). Your Warlock Pact Magic means that you will always have a 1st level spell slot available after a short rest, which is great because even if you are deep in a dungeon, you can always have one trick up your sleeve.

A one level dip is not going to dramatically impact your Cleric's abilities to cast spells, and as you level, that will become more apparent. Low levels are always dangerous.

RP is good, but you should also consider what your role in the party ought to be and possibly talk to your DM about "retraining" to better fit that role. Choose a "Primary" and "Secondary" skillset and make sure you can do those things reasonably well. Everything else can easily be fluffed around that.

Forgot to mention:

The spell Hex adds an additional 1d6 damage per attack, so:

If you use Chill Touch at 5th level, that's 2d8+1d6 (Average 12.5).
If you use it with a spell like Eldritch Blast, that's [1d10+1d6]+[1d10+1d6] (Average 18).
If you use it with both Eldritch Blast and Agonizing Blast, that's [1d10+1d6 +4]+[1d10+1d6 +4] (Average 26).

If you chose Cleric (Knowledge Domain) for a reason, I would recommend asking about restating and dropping Warlock altogether. Focus on Wisdom and just go pure Cleric. Getting access to higher level spells is extremely satisfying.

However, if you aren't allowed to reallocate your stats, I would recommend asking about swapping your Cleric Levels out for Sorcerer (Divine Domain), as you'll get access to Cleric spells, as well as Sorcerer spells, so you could end up with both Raise Dead and Wall of Fire, which will definitely cover your bases for Healing and Damage dealing.

Beyond that, if your character is focused on immortality and "power over death", you might want to consider rebuilding from scratch as a:

Wizard (School of Necromancy) for the study of unlife, or;
Wizard (School of Transmutation) for the "philosopher's stone" path to immortality.

Transmutation Wizards get the Master Transmuter ability at 14th level that gives you access to "Restore Life" (Raise Dead), "Panacea", and "Restore Youth" (Doesn't extend lifespan). It doesn't actually grant immortality, but hits all of the hallmarks of the search for eternal life.

Try building a 20th level character to represent your "goals and dreams", and then work that back to the level you are actually playing at, so that you know what you have to look forward to and what drives you. (Spells, feats, class abilities, etc.)

The bottom line is, "Play something fun". Build yourself a character that can spend some time in the spotlight, but don't worry about being optimized for every role.

Quote from Surfanicar >>

Quote from Memnosyne >>

"Multi-Classing" as Warlock/Cleric is definitely not optimal, as they will split their resources between Charisma and Wisdom, but whether or not it's 
dumb" depends on the particular build. Hexblade is frequently used as a 1 level dip for melee builds. However, since you're not really built for melee, it won't benefit you nearly as much. Going into Warlock, you gain access to the best Cantrip Damage spell, Eldritch Blast. If you take one more level, or take the Eldritch Adept feat, you can gain access to the invocation Agonizing Blast, which will scale in damage similar to a ranger or fighter.

With your high Charisma, you might have been better off choosing Sorcerer with the Divine Soul origin to tie the Cleric spell list with your attribute strengths. (Look up "SorLock" guides for similar builds.)

As built, your character is vulnerable to Grappling and Dexterity Saves, which means you could be in trouble in both melee and against AOE spells. (Web, for example, will cause you lots of problems.)

That said, you shouldn't have any issues with healing at your current level. You have access to Cure Wounds and Healing Word (Great for reviving fallen party members). Your Warlock Pact Magic means that you will always have a 1st level spell slot available after a short rest, which is great because even if you are deep in a dungeon, you can always have one trick up your sleeve.

A one level dip is not going to dramatically impact your Cleric's abilities to cast spells, and as you level, that will become more apparent. Low levels are always dangerous.

RP is good, but you should also consider what your role in the party ought to be and possibly talk to your DM about "retraining" to better fit that role. Choose a "Primary" and "Secondary" skillset and make sure you can do those things reasonably well. Everything else can easily be fluffed around that.

 Dang thank you this is really helpful, I may ask if I can re-do my lvl 4 advancement and go into sorcerer as that still would fit into the RP aspects I think. The eldritich Blast aspect you mentioned is pretty awesome! And as a nerd, I did want to summon some demons haha

Do you think I should just continue on then with what I have or try and re-train my guy? I think the primary thing is to heal, and secondary would be damage but we honestly have a lot of close calls due to healing (because no one has potions lol). 

 Potions and hit die should be the primary means of healing. One of the most efficient healers in the game is the Life Cleric and even their heals are better in support. If your bard has Bane and casts it regularly, Bless is a good complementary spell as it will increase the saves that each affected teammate makes as well as increases the accuracy of their attacks. Bane dec decreases the accuracy of the attacks of the affected creatures and decreases the saves that they make.

A 19 DC is pretty good. At 4th level with a 12 con score, you should have 30 HP which isn't awesome but it's not terrible either. If you are a Hill Dwarf, you would have an additional 4 HP. A good spell for a Cleric to cast at that level is Aid. Addtionally, you could go Cleric 4 at your next level to get your ASI and choose Inspiring Leader from the list of feats. With your high charisma, you would give 9 temp HP per rest at 5th level, and it would increase by one for each level you gain as well as when you get your charisma to 20.

I would likely stay at range since your melee stats are terrible (unless you went hexblade), and your speed will be somewhere between 15 and 25 meaning you won't be able to clear as easily if being attacked. At 5th Cleric, you would be able to take Spirit Guardians to help with that as it would slow creatures down within 15 feet of you and deal damage to any that start their turn in that area. 

Edit: Not sure why I thought that they had heavy armor. Speed will be between 25 and 40 likely then (also not sure why I didn't think about a possible race with better than 35 speed since there is at least 1).

My pleasure! :)

I also recommend checking out the "Class 101" articles written by James Haeck here on DndBeyond. [Cleric 101: Knowledge Domain]
They can provide you with a well-rounded understanding of the class' strengths and weaknesses to help guide your progression.

Since this is your first character, here is a couple more pieces of information to keep in mind:

1) Your Spell Slots will continue to grow with your Character, so long as you multi-class into another full Caster class (Wizard, Druid, Sorcerer, Bard, [1 level of Artificer]). This means that you can dip into one of these classes without losing potency, even if it slows your spell progression slightly.

A Cleric 5/Wizard 5 will be able to cast 3rd level spells from both the Cleric and Wizard spell lists, but will have access to (3) - 4th level slots and (2) - 5th level slots that can be used to upcast those lower level spells. (5th level Fireball would deal 10d6 damage, and a 5th level Hold Person could target 4 humanoids simultaneously.)

Since Warlocks use Pact Magic, they don't advance Spellcasting, so it is important to understand the pros/cons of multiclassing with them.

2) Your Ability Modifier increases with even Ability Scores. This means that if you already have a Wisdom of 16(+3), a "Ring of Wisdom" that increases your score to 17(+3) doesn't actually benefit you mechanically. I suspect that this is a Homebrew magic item, so if it actually provides "+1 Wisdom", then you would be better off splitting your ABI to +1 Wis +1 Int, so that you end up with a total of Wis 18(+4), Int 14(+2).

The only time that odd ability scores really matter is in the case of calculating Carrying Capacity from Strength.  (Carrying Capacity equals Strength Score x15)

3) The Fighter and Monk in your party are going to be getting a lot of attacks from Extra Attack and Flurry of Blows, so sometimes the best way for you to deal damage is going to be boosting your allies, rather than pumping out damage yourself. As Jhfffan mentioned, spells like Bless might seem weak on paper, but actually make a big difference in play. 

You also gain access to one of my new favorite spells Command, which is incredibly flexible for its level:

"Approach" can force a target to trigger Attacks of Opportunity from your allies, or force it to walk across an imaginary bridge.
"Drop" can force a BBEG to drop a magic staff or relic, allowing your Monk to snatch it up and totally flipping the encounter.
"Grovel" grants melee attackers advantage on all attacks for a round.
...and if you need something that isn't listed, you can try any one-word command that you can think of.

Best of luck, and may the dice be ever in your favor!

I want to add here that you can keep all that RP goodness with a pure cleric. Anybody in any class can be overly ambitious and get in over their heads. Any class can make a deal with someone. Warlocks actually have no mechanics to go with the RP side of their pact - like what they might owe their patron or how to break the pact.

Think of warlock like a pre-packaged microwave meal that contains readymade RP elements. Just because you want some of those elements doesn't mean you can't cook up something at home with the same RP ingredients but different mechanics. It might even taste better.

You need to re-examine your character.   I do not know why you think necro damage is a good idea.  If it is just for RP reasons, that reads like a crazy person, not someone trying to achieve immortality.     What would you think of a soldier that refuses to shoot people, instead insisting on drawing his knife and stab them to death?  That guy is obviously insane.  You use your best weapon, not the one that looks prettiest.

Toll the Dead is a good spell for you to be using, at least till you upgrade EB.

If you take a 2nd level of Warlock you should be using Eldritch Blast a lot, particularly once you hit 5th level.     Inflict Wounds is designed for a high AC character with high HP.  That is not you, do not use it, instead look at Guiding Bolt.  

Also do not use Witch bolt.  It was great at 1st level and sucks by the time you hit 4th.  

But the single most important thing you should be doing is obtaining a Rod of the Pact Keeper.  It is +1 to hit and +1 to DC of saves with all warlock spells - even those cast with a cleric slot.  It also lets you recover one warlock spell, which is nice.

Those spells include Toll the Dead, Eldritch Blast AND Hold Person (2nd level Spell).  Later it will include Banishment

One of my players is this exact split (Knowledge cleric 3/Warlock 1) for RP reasons. It is not mechanically optimal but he does great. 

Typical battle starts with Bless. Harder battles get Spiritual Weapon up right away. Then he either eldritch blasts or heals (or uses Command or Suggestion or Silence). Guiding Bolt and Hellish Rebuke add to damage when needed.

if this is your first character remember, as a cleric, you can switch your leveled spells on a long rest (at 3rd level cleric you have 1st and 2nd level spells) so if you want to do more support, lean on the hex/eldritch blast switch out other spells for support. cantrips you are stuck with unless your DM allows you to switch. Or I think Tasha’s has rules for that, I think 

when you hit level 5 you could take your 4th level in cleric and maybe boost your DEX so you don’t have a minus 1 to AC and initiative. Or take a feat that gives a +1 to DEX and a feature. 

Personally I don’t think you made a mistake, splitting between WIS and CHA isn’t that big of a deal, but as you are finding out, that focus keeps you from being a front liner. 

Cleric is one of the classes I never multiclass. It is just too powerful in itself and what it gains from other classes just makes it take long to hit.  I have literally seen my cleric tear up opponents with guiding bolt with a teammate following up to take advantage of..well advantage. Spiritual guardians, spiritual weapons, toll the dead, inflict wounds....all great damge options.  Oh then throw in their heals and massive utility and there is no reason to multiclass with bard.

Now, other classes taking a level of cleric - awesome way to did.  Just not the other way around.

And a 19 AC at your level is nothing to feel squishy about especially with how low your strength and dex are.  I am actually kind of wondering how you have an ac that high with no heavy armor (strength too low) and a dex that actually reduces your AC by 1 with any of the armors you can wear.

Quote from Grebeir >>

Cleric is one of the classes I never multiclass. It is just too powerful in itself and what it gains from other classes just makes it take long to hit.  I have literally seen my cleric tear up opponents with guiding bolt with a teammate following up to take advantage of..well advantage. Spiritual guardians, spiritual weapons, toll the dead, inflict wounds....all great damge options.  Oh then throw in their heals and massive utility and there is no reason to multiclass with bard.

Now, other classes taking a level of cleric - awesome way to did.  Just not the other way around.

And a 19 AC at your level is nothing to feel squishy about especially with how low your strength and dex are.  I am actually kind of wondering how you have an ac that high with no heavy armor (strength too low) and a dex that actually reduces your AC by 1 with any of the armors you can wear.

 

 They can wear heavy armor with their strength that low, but their speed would be reduced by 10 unless they were a dwarf. However, knowledge cleric and warlock don't give heavy armor proficiency. They would have to be human variant with the heavily armored feat, but that gives a +1 to strength. I guess they could have had a 7 strength to start if they rolled, which would account for the 18.

As for medium armor, 14 + dex modifier for scale armor would give a 13 AC, a shield would push that to 15, a plus 1 from warforged perhaps and maybe +1 armor gets to 17 then shield of faith to get to 19? Could also be the staff of defense. Who knows. 

I think you can keep what you have but as some others have suggested it would be good to pick up spiritual weapon (SW) so you can cast it as a bonus action (yes it conflicts with hex but it’s a d8+WIS modifier damage) and you can cast eldritch blast (EB) as your action getting two attacks the first round. And you can repeat that each round. Once you hit 5th level cleric Spirit Guardians (SH) is good. That and spiritual weapon are a nice combo. And I think once you are concentrating on SG you can still attack with SW and Eldritch Blast

edit: I believe you can on round 1 cast SG and EB. Round 2 concentrate on SG, cast SW and attack with it, and EB as well. So you have 2 sources of damage round 1 and 3 sources of damage round 2 

someone please correct me if I have any of that wrong. 

oh, and you can flavor your SG as spirits you are dealing with to obtain your immortality, or something like that. You summon them so they can feed on your enemies to gain power for your transformation. 

Quote from ThriKreenWarrior >>

I think you can keep what you have but as some others have suggested it would be good to pick up spiritual weapon (SW) so you can cast it as a bonus action (yes it conflicts with hex but it’s a d8+WIS modifier damage) and you can cast eldritch blast (EB) as your action getting two attacks the first round. And you can repeat that each round. Once you hit 5th level cleric Spirit Guardians (SH) is good. That and spiritual weapon are a nice combo. And I think once you are concentrating on SG you can still attack with SW and Eldritch Blast

edit: I believe you can on round 1 cast SG and EB. Round 2 concentrate on SG, cast SW and attack with it, and EB as well. So you have 2 sources of damage round 1 and 3 sources of damage round 2 

someone please correct me if I have any of that wrong. 

oh, and you can flavor your SG as spirits you are dealing with to obtain your immortality, or something like that. You summon them so they can feed on your enemies to gain power for your transformation. 

 Spirit Guardians is an action as is Eldritch Blast. You'd only be able to cast one first round. To maximize damage and action economy, you'd want to cast Spiritual Weapon and Eldritch Blast first round and then Spirit Guardians the second round while using your Bonus action to attack with Spiritual Weapon.

I'd activate Hex first round if you aren't using another concentration spell like Spirit Guardians during the fight and want to cast Hex. You can then cast Spiritual Weapon second round if you want to cast it to give you a consistent bonus action attack. At fifth level (Cleric 4/Warlock1 or Cleric 3/Warlock 2), that will give you 3 total attacks affected by Hex for 2d10 + 1d8 + wis +3d6 (+ cha x2, if Warlock 2 with Agonizing Blast) damage spread up to 3 different targets. With a 16 wis and an 18 cha, that's 29 (37) average damage starting round 2. That'll drop 10.5 average damage with Spirit Guardians up instead of Hex, but Spirit Guardians does it's own damage and is great crowd control. It's a great deterrent for a backline tank with a few casters or ranged characters to protect.

Just remember that not every fight will require casting any of these combinations or even more than cantrips. See how the DM likes to play certain enemies and how your party likes to handle different situations and adjust accordingly. 

With lots of smaller and weaker mobs, you may want Spirit Guardians up. With 1 or 2 stronger enemies, it might be better to go hex or Bless. There are lots of options to look into. 2 levels of Warlock aren't bad for a Cleric. Getting the second level for invocations allows for Agonizing Blast which increases your damage with EB significantly. The second could be Repelling Blast to add some support onto your EB spam or Fiendish Vigor to give you some temp HP (not as tempting if you go with the Inspiring Leader feat as they don't stack, though you can use fiendish Vigor to increase the temp HPs once they dip below the amount that 1st level False Life can give you), as well as a few others. EB is a better ranged option than Toll the Dead or Sacred Flame, though either makes a good back up to EB.

Jhfffan, 

thanks for the correction. I figured I had something off but was in a hurry. Great advice too.