I myself was raised a Christian, I even tried pretty hard to be a good one. At about the age of 15 I was influenced by an older gentleman who was a devout believer in Jesus Christ. He told me that there had once been a time in his life when everything he touched fell apart and he was totally lost. He believed that he'd been rescued from his pain and suffering through a belief and a personal relationship with god.
This gentleman actually drove the bus that took me to school in the morning and so I got the chance to really get to know this person and who he was. What a true gentlemen this man was, even though I now completely reject his belief in a christian god. He was totally committed to his beliefs, he gave up women, liquor and several other things he considered vices all in an effort to live a godly life. After talking about the scriptures with him for a time, I became motivated and inspired to find god.
So I attempted to read the Bible in its entirety, my purpose wasn't just to read the scriptures for the sake of reading the scriptures I was trying to get closer to god. Even though my life was rough at the time I wasn't asking for help from god to get out of my personal situation. I just wanted to live a righteous life and to do right by god. Eventually I ended up spending about 3 months trying to read the entire bible although I never did finish.
One night while reading the scriptures, I began to get sleepy ( it was about 10:30 pm and I had school the next day). During that night I begged god to appear to me or show me a sign that he actually did exist. What I got in return was absolutely nothing, no message, no sign that god existed at all.
Although I didn't De-convert that day, it really started to bother me that an all powerful god who wanted me to know him, love him and praise him would refuse to reveal himself to me in some sort of fashion. It really bothered me that a loving god could hear me begging him to reveal himself but then ignore me completely during a time of confusion and mental anguish.
I didn't become a non believer that night but the fact that a loving god could ignore his child begging him for answers was really the beginning of the end of my belief in god.