Secular Domain (Ur-Priest)

A Cleric of faith you most certainly are not. Rather, you've found a way to tap into the lingering power of "Outsiders" that have long used both the mortals and immortals of your realm like puppets. Where other cleric domains worship deities, you've found your way through by holding up ideals viewing divinity to be a falsehood. Proselytizing your revelation to others, espousing the notion of turning away from gods for the sake of more secular values. Your magical prowess is not granted by divine favor but by the power of your closely held convictions.

Lesser Spell Resistance

The strength of your conviction forms a protective barrier around you, shielding you from magic. When you make a saving throw against a spell or other magical effect, you may roll a d4 and add the number rolled to your saving throw. This feature doesn't work against spells cast by other Ur-Priests.

Channel Divinity: Turn Outsiders

Starting at 2nd level, you can use your Channel Divinity to turn extraplanar creatures.

As an action, you present your holy symbol, and one celestial, elemental, fey, or fiend of your choice that is within 30 feet of you must make a Wisdom saving throw, provided that the creature can see or hear you. If the creature fails its saving throw, it is turned for 1 minute or until it takes any damage.

A turned creature must spend its turns trying to move as far away from you as it can, and it can’t willingly end its move in a space within 30 feet of you. It also can’t take reactions. For its action, it can only use the Dash action or try to escape from an effect that prevents it from moving. If there’s nowhere to move, the creature can use the Dodge action.

Banish Outsiders

Starting at 5th level, when a creature fails its saving throw against your Turn Outsiders Channel Dvinity feature, that creature is banished for 1 minute, as if affected by a banishment spell, if it isn't native to the plane of existence it currently occupies, and its challenge rating is at or below a certain value depending on your cleric level, as shown on the table below: 

Banish Outsiders

CLERIC LEVEL	BANISHES CREATURES OF CR …
5th	1/2 or lower
8th	1 or lower
11th	2 or lower
14th	3 or lower
17th	4 or lower

Divine Spell Siphon

At 6th level, you gain the ability to magically steal the knowledge of how to cast a divine spell from another spellcaster.

Immediately after a creature casts a divine spell that targets you or includes you in its area of effect, you can use your reaction to force the creature to make a saving throw with its spellcasting ability modifier. A "divine spell" is any cleric, druid, paladin, or ranger spell, or spell cast innately by any celestial or fiend. The DC for this saving throw  equals your cleric spell save DC. On a failed save, you negate the spell's effect against you, and you steal the knowledge of the spell if it is at least 1st level and of a level you can cast (it doesn't need to be a cleric spell). For the next 8 hours, you know the spell and can cast it using your spell slots. The creature can't cast that spell until the 8 hours have passed.

Once you use this feature, you can't use it again until you finish a long rest. You can't siphon cleric spells from other Ur-Priests, but you can siphon a spell cast from the druid, paladin, or ranger spell list, even if the caster is also a cleric of the secular domain.

Combat Caster

Starting at 8th level, you add your Wisdom modifier to the damage you deal with any cleric cantrip.

Spell Resistance

Starting at 17th level, you have advantage on saving throws against spells. Furthermore, you have resistance to damage from spells. This feature doesn't work against spells cast by other ur-priests.