Can you pick a patron deity if you aren't a priest?

[Guest Ontarah]

Neverwinter Nights had this.  I always wished Pillars did given how much gods matter in this universe. 

[LordBlade]

You couldn't in the first game, so I doubt you can here. Which is disappointing.

[EightBolts]

Probably not. Wouldn't make much sense to do so considering your history.

[Balbanes]

You could with some cheating! PoE1 tracked priest and paladin orders separately from class, so you could set those fields (via editors and maybe console commands) and the game would give you corresponding dialog options. Not sure if that still works in PoE2, given that they're subclasses now.