I think the issue here is, once you have been properly brought up with faith, 'indoctrinated' so to say, it becomes part of your core personality. You can't live rest of the life without it, there would be a gaping hole in your heart and mind that screams to be filled in +-similar way heroin addict feels the need to get another fix.
On the other side, being brought up in environment where (a bit religious non-practicing) parents extorted 0 influence over me and let me find my own belief (or lack of it), I really don't have this 'hole', nor the need to put author on everything I see around me. Matter can self-organize pretty well on its own and we currently don't have a good mind capable of comprehending true complexity of interconnected reality of our universe.
I could cross over to faith group (as did my cousin who was brought up in similar environment and is now priest happily), but every single cell of my brain would have to be vaporized for me to be OK with it for rest of my life, when I see glaring proofs around me every day that tell me there is no creator in the form all major religions imagine/hope for.
And whether there is another type of creator, is a question that is not that important for me, since answer to it won't change a single thing in my life, nor my morals nor any behavior or decisions. We all (sane human beings) have a moral compass, and apart from the part about believing in one and only true god, it aligns pretty damn well with most religious moral doctrines.
I don't think true believers can ever come to state of mind to even seriously toy with the idea that there might not be immortal soul of them. That its only this world, and nothing more, no higher meaning or purpose. That we are not special, and universe will be just fine even if Earth is consumed by black hole tomorrow afternoon. They just can't do it and be happy full people anymore.
I can, easily, without a blink of an eye, and it feels great and empowering. Even if I may be wrong, which is not a bad outcome after all :)
Sorry for the long post, just putting down some observation between agnostic me and my fiancee who was brought up in pretty strict catholic ways.