"I honestly couldn't believe most of it and felt like a fraud and an outsider."
I was brought up in a very Christian family and couldn't see the point of religion except for the social gathering of nice people. I asked awkward questions about the silly bits in the bible and was told that they were perfect examples of the opportunity for faith, ie accepting something as right and true whilst the evidence would point to the contrary. I honestly couldn't believe most of it and felt like a fraud and an outsider.
As an outsider but still dragged to church by my parents I started to (as objectively as possible) observe what went on in the services- synchronized standing up, kneeling down, reciting nonsense and realised that it was finely tuned brainwashing interspersed with readings from a "holy" book and sermons. I gave the brainwashing and group dynamics a chance to work and waited for the cynicism to fade but it never did.
Over the years I looked at other religions and they all seemed silly too. The time and effort that went into minutely examining all the holy books and the misery caused by the arguments between the religions seemed pointless. The evil results of the religious teachings (Fatwa, Jihad, contraceptive bans etc) and the foul behaviour of some religious leaders (child abuse, extorting money from followers etc) disgusted me.
Science and reason played its part too and I read work by intelligent people that didn't rely on "faith" to convince me. I learned that atheism was a sensible position that had been held much longer than Christianity and the other major religions. I don't believe in a god, but am quite prepared to be proved wrong with credible evidence. Every time someone is beheaded in the name of Allah or mutilated in the name of Judaism or discriminated against in the name of Christianity it becomes more certain that even given absolute proof of god I wouldn't worship it.