Believe it or not, I too was into the whole, "good little Christian boy" thing. I just managed to wise up several years before she did. I was actually about 10 or so when I started seeing major plot holes in christianity. Actually, the reason she left religion had nothing to do with being a lesbian.
Even though I did unofficially leave christianity, I still held some belief in a higher power. I had gone to a "healing" seminar (yes, ridiculous I know). I had just recently been diagnosed borderline diabetic. While at this seminar, I was seemingly healed. I went to the doctors the following day and everything came back 100% normal. They could not explain this. Due to this, I temporarily believed once more. I truly felt I had been healed by God. 1 week later, I was fighting for my life after being dead for 14 minutes. If it were not for CPR and defibrillation, (multiple times over the course of that 14 min) I would be permanently dead. My mom was enraged that any possible god having me believe I was healed only to take it back and give me full blown diabetes, was not a god she was going to believe in. That is why she left. It also solidified my anti-beliefs. Can I explain why I was "cured" temporarily? No. There is a LOT we have yet to understand about science and medicine. But one thing I do believe, no loving God would do to me what happened. And if there would be a god that would heal only to take it back ten fold, I want no parts in.