My player is trying to play a paladin but doesn't want to be religious, he wants to be an oath of conquest and make it to himself. If this is possible, and someone explain me how some random person can just swear an oath to themselves without any divine intervention and be granted these magic powers.

Mechanically it does not seem to break the game. It does, however, fly in the face of the spirit behind the class. Personally I would discuss the idea of being a pure fighter, as that seems to be what he is describing. Also you may want to indicate (if it is true) that there are rewards for great role play, and this obvious "inconsistency" may be a disadvantage in that pursuit.

In short; allow anything that doesn't break either the rules or your game, but let the player know that you don't "get" their character choices and that may effect their experience.

Cheers and good luck

I don't think a paladin needs a god to mediate their interaction with magic. Their Oath itself is the source of their power.

"a paladin’s oath is a powerful bond. It is a source of power that turns a devout warrior into a blessed champion." - https://www.dndbeyond.com/characters/classes/paladin#PaladinClassDetails

The description of the Oath of Conquest itself explicitly allows the paladin to be committed to a philosophy, rather than a god:

"The Oath of Conquest calls to paladins who seek glory in battle and the subjugation of their enemies. It isn’t enough for these paladins to establish order. They must crush the forces of chaos. Sometimes called knight tyrants or iron mongers, those who swear this oath gather into grim orders that serve gods or philosophies of war and well-ordered might."

So, yeah. As written, random person can swear an oath to themselves without any divine intervention and be granted magic powers. But the silliness of that statement comes from intentionally phrasing it in a silly way. It's up to your player and you as a DM to find a way to phrase that which sounds more credible in your world. Fortunately, the existing material about how paladin powers work already does much of the work for you. Paladins are so devoted to their causes that that devotion itself is strong enough to allow them to draw on its power to achieve magical outcomes.

Sounds more like a Fighter/Sorc. All of their power really does come from within, with no need to twist words. 

Agreed, it's all in the wording. An oath has 2 parts, an objective and an audience. i.e. swear to uphold justice and vanquish evil, and this can be sworn to a deity philosophy etc. 

Swearing an oath to yourself sounds like you are granting yourself magic powers, when it fits better to say the unintended audience, a philosophy or even a deity you don't pray to, is pleased with your oath objective

Sorry I'm just having a tough time wrapping my head around the idea of a fighter just making an oath to himself to get powers. To me it seems like a warlock that doesn't have to go through the hassle of dealing with a patron, and instead the player just decided he has magic if he does x things.

It's your game =)

Sounds like having cake and eating it too.(warlock without patrons)

As discussed a paladin, oath of conquest, does not need to name a deity, philosophy or anything else to be granted powers. The origin of these powers need not be specified, though they ARE a divine power: phb, magic

The spells of clerics, druids, paladins, and rangers are called divine magic. These spellcasters’ access to the Weave is mediated by divine power—gods, the divine forces of nature, or the sacred weight of a paladin’s oath.

And any oath as a fighter would not result in gaining powers, not sure where that came from tbh.

You can say OK, then later reveal that his powers came from Asmo.

the thing about an oath is that you're binding yourself to a certain accountability, usually a power you believe to be greater than yourself. what that power is is up to the oath-taker. it has to be greater than you in order to actually enable accountability. calling an oath on yourself is basically just like promising yourself you'll do more exercise and help the poor. that promise is only as good as you and if you're not worth your own salt, well the oath means jack. so if this person wants to take an oath, it had to be to someone or something that can make the player accountable for their actions.

Quote from Mandalore26 >>

Sorry I'm just having a tough time wrapping my head around the idea of a fighter just making an oath to himself to get powers. To me it seems like a warlock that doesn't have to go through the hassle of dealing with a patron, and instead the player just decided he has magic if he does x things.

 It sounds like you're being selective in where you can and can't suspend disbelief. That's cool, it's your world. You can say that oaths aren't magic just like you can say that dragons have jetpacks instead of wings, as long as you acknowledge that it's a variation on the default and clearly communicate your vision to the player.

Have you heard of Tinel? (Ref. The Book of the Righteous: A complete pantheon for fifth edition.. Published by Green Ronin Publishing, Pg. 75)

He is essentially described as a God of knowledge and seeking self-betterment.. he doesn't really have any interactions with his followers. Well, since the character is "Self-Devoted", and every oath needs an audience (very well said Gigaflop) here your player will find a God who wants the character to better and improve on himself, eventually aiming to join the character with them in the God-verse. His symbol is a key, but hell, you can explain that the character's mind it's self is a key; eliminating any need for religious symbols on the person.

There is more to Tinel, if you care to delve, but he is quite ambiguous. If all you need is a way to tie the player's desire into the character, I might try this. Hope this helps!

"Your player calls out into the multiverse, pledging his oath to his own proud name. At first, there is no power, no answer to his heartfelt oath. He sits in silence for a moment, only to feel his mind open, almost as if tearing. Roll Constitution (9) - Pass: You brace yourself as you fold your mind into the open tear. Fail: You collapse, and awaken to a what feels like a scar upon your mind. Encourage to try again.. maybe investigate... Roll Wisdom (12)- Pass: You can see a great figure before you 'I hear your proud cries of promise, and bless your path. I require only of you to stay true to your oath.' You feel great power sear through you. It is pleasant and exciting. Fail: You hear a mocking laughter. Nothing about you changes, and you are left in silence."

If my player doesn't take the oath from a god but rather himself, my problem is that it seems like their is no risk in that. If he breaks the oath, he can just swear another to himself?I just feel that if someone can promise to themselves to conquer, and just receive powers from themselves to do it, wouldn't there just be tons and and tons of conquer paladins walking around. Maybe if during battle he saw injustice and swore to a god to give him powers like Kratos from God of War, or maybe he found some sort of contract to sign to get these powers, but then that starts to seep into warlock ideas. I think my concern is the whole, just a random joe getting powers. I guess I should reiterate my first concern which was, does a paladin have to be religious at least. I would let the idea of them making an oath to a philosophy, but don't they have to at least be religious? Or are there conquer paladins that don't pray to a god?

It’s YOUR table never let a player bully you. Talking, negotiating, that’s fine, but if there is something in your game that a player wants you to change for his personal gain, too bad, he can run his own game. 

If he wants a character that has power from within, he can play a sorc, a fighter, or a monk.

"religious" is subjective 

to a god of war, a character may be considered a devout, should that character participate in wars destruction violence etc.

the relationship need not be reciprocated by the character. 

essentially an oath to conquer, regardless of who it is "to" is invariably "heard" by the granting power, in the above case:

the character swears an oath to conquer (to himself) the God of war hears this oath and decides to grant Devine powers. the character does not necessarily know where these powers came from. if the character breaks his oath or changes it in any way; the granting power decides what to do... which likely means the character can stick with the original oath or be an oath breaker.

I've always been fascinated with the morality of a paladin of a god of war, especially if the paladin is not evil. I'd love to have a discussion about that by itself. In Pathfinder, I play an inquisitor of a god of war and I've spent hours trying to get into my character's head and work out his justifications for doing what he does.

As for the thread topic, I'm very ambivalent about this. On the one hand, if it works mechanically and the player wants to do it, my instinct is to let the player do it. But at the same time, a paladin channels divinity, which explicitly references the divine. This is the kind of paradox that is ripe for the DM to lay at the feet of the player and say, "Make me understand where your character is coming from." If the player can't justify his own character, then it's a pretty shaky premise. If the player comes back with an interesting concept, then the character and the campaign are better off for having it.

Something to remember is that "not religious" doesn't mean "atheistic"
The paladin may not WORSHIP a god, but could theoretically WORK for one, like a warlock works for their patron.
Considering the gods are known, for certain, to exist, anyone who doesn't believe in them is either in denial of reality, or simply insane.
But they might not feel the gods DESERVE worship
So if it were my story, I'd have the character swear an oath to live up to whatever ideals he's meant to be upholding, and have him catch the attention of a patron
the patron then offers their power because their goals and the character's align. This then changes the paladin, allowing him to channel divine power, and he can acknowledge the AID he receives, but still insist that the god should not be worshiped.
This also gives you a potential conflict later: perhaps the god grows weary of the character's arrogance, or his insistence that it's HIS power, not the god's, that enables his success, and so the god takes their aid away.
But paladins ARE forces of will, and so he manages to hang on to bits of his god-given power, becoming a fallen paladin. then you can have him searching for ways to reclaim his "stolen" power

Firstly, the mechanics of a Paladin do not actually require a physical oath to have ever taken place, nor is a god required. Likewise the mechanics of a Warlock needs no specific patron, a Cleric any god, a Druid any particular devotion or affection for Nature, and so on. They are all just mechanics, the color that surrounds then is up to you all collectively to define.

So, how could you think of a Paladin with an Oath to nobody? Easy enough. A Paladin's Oath is not just any oath. We know this this because characters in this game are able to say "I swear..." without accidentally becoming a Paladin. A real Oath is one that comes from the soul, and that resonates its power out into the multiverse. Maybe there are rituals involved, years of training, holy orders, etc. or maybe a young girl kneeling in the ruins of her family home, beside her slain parents and cradling the corpse of her baby brother swears an Oath so powerful that it reaches deep into the divine realms and draws power to fuel her need for revenge.

So, ask your player to provide a backstory with sufficient drama to result in so powerful an Oath. With that material you have just as much (if not more) opportunity for quest hooks and role-playing situations than you would if the player just named a god. You also still have a mechanism to ensure the Paladin keeps their Oath, and in desperate and story-appropriate situations, perhaps the powers of the Oath could abandon them until they get back on track.

I'm still debating the idea of a paladin that can make an oath to himself/philosophy so long as the player acknowledged that it came from a God. But isn't the whole deal of warlocks and clerics, is that they get their powers from higher deities. The cleric even gets the feature of divine intervention where they ask their God for help. Wouldn't that mean that having a God is needed to play cleric? 

For oaths of conquest it's easily covered by having a god of war take interest in the oath and deciding to support them, though it doesn't have to be a war god who picks up the tab, it could be someone like asmodeus if you want to make their life hell,  then you could give them a few levels and then send him an imp for a chat.