|Get off your high horse, Turpin.|
Rather, you've made a Faustian deal that saved your Aunt Stacy's knitting store from foreclosure and now some pompous, immortal a-hole owns your soul. You know that using the "divine" powers for which you paid so dearly ever-increases your malicious patron's grasp on your being, but you can't check your self-destructive behavior. Or maybe that's his growing influence at work.
Or maybe your grandfather was the byproduct of a tryst between Zeus and a rather adorable parlor maid. Though you've never met Great Granddad and he certainly doesn't know of/care about your mortal existence, you've inherited enough nascent divine favor to crank out the occasional heal wounds or fire storm.
Or you're just a guy who's found a cosmic loophole that's allowed you to hack into the server of the divine realm. You've spliced into Odin's cable box and you're watching ESPN: Old Norse on The All-Father's dime. Maybe one day Asgard's IT staff will secure its wifi and damnation will be served. But, increasingly, you're coming to believe that the gods are just guys like you; guys who've figured out how to hotwire the cosmos to their advantage. Guys who've achieved immortality by convincing the world that they're something special, and who've come to believe in it themselves.
Of course, you can limit yourself to the holier-than-thou, preaching-the-faith-in-exchange-for-cure-light-wounds scene if you want to. And maybe you can justify why your sermonizing n' moralizing minister is wandering through the 5th level of FU2: Asylum of Turgid Munchkins helping a party of infidels murderize a colony of troglodytes and scarf up their treasure--spoiler alert: not likely. But the point is, there are other options besides the worn out catholic-priest-with-a-mace that those TSR beardos foisted on us way back when. Try one on for size.