I always liked the idea of the faith of humans giving power to gods.
But maybe what if it is a little different - the faith in a god (or a similar concept) gives strength to the community of the faith? Not an individual creature, but the community.
That's why churches form - the devotion of the faithful is what creates a source of power that people chosen by the community can tap into by being ordained. This power doesn't have to be aligned with the faith - it just exists, but requiring faith to be created.
Members of the church don't have to be lied to by priests -the priests can tell them outright - you know, you can believe in what you want, gods don't exist, but if you focus your mind on the ideals represented by our Church, you create a source of power that will help us all!
Good people would of course try to align the faith with good ideals - justice, valor, honesty, since the ideals alone would already benefit the community. But that's not a requirement. It might also be a good idea to "believe" in egoismn or might makes right, since this would attract egoistic people.
And of course, you could also worship objects of less moral relevant - beauty, art, song, dance, nature, sun, moon, earth, fire and so on, because people can appreciate this, too.