For me, religion has always seemed like a significant other. Some people pledge devotion to their one true love in high school and that's it. Some have one love for awhile, then switch in middle age. Some take awhile to settle down, but when they do, it's for life. Some never completely commit to anything and flit from faith to faith (I privately think of such people as Beliefsluts.)
One of my YRUU folks said the other day that he was his girlfriend's "pet" because she has decided she doesn't believe in love. After telling him the story of the time I as a ten-year-old announced at the dinner table that I had decided I didn't believe in marriage and wanted to live with another woman when I grew up and how my parents freaked out, I said that people often make rash decisions about such things when they are young, but my advice would be to not let oneself be a pet to early and wait and see if the girl who doesn't believe in love comes around.
I tend to think that people who flat out decide they don't believe in organized religion have a similar maturity level to that girl.
Ideally, you find a faith and really get to know it and stick to it, but sometimes things change.
Anyway, Owen Edgerton nicely plays out this theme in this essay.