I'll let Dan Barker answer that one; from his book, Godless.
Since I have become an atheist I often hear from believers who tell me that I could not possibly have been a true Christian or I would never have left Christianity. If I had truly known Jesus personally, like they do, then I would never have denied him. I must have been merely pretending to convince myself that God was real, they insist. Well, yes, I know exactly what they are saying. I used to preach that sermon. I preached it, believed it, knew it and felt it. If I did not have an authentic relationship with God, then why not? Why would God reveal himself to them, and not to me? I read the same bible, prayed with an open, humble spirit, and received inner confirmation of a “presence” witnessing to the truth of what I believed. If what I felt was phony, why would a good God allow me to be so deceived? (And how does anyone else know they are not being deceived as well?)
I had no doubts at all that what I experienced was authentic, not until near the end of my ministry. I sometimes ask these people, “Who are you to decide who is a true Christian?” Jesus said, “Ye shall know them by their fruits” and my life exhibited the “fruits of the spirit.” Paul wrote that “the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, temperance: against such there is no law.” I was not perfect—nobody is—but judging by the bible, no one else can make a stronger claim to being a Christian. I had been “born again” and believed it and announced it. I had been “filled with the spirit” and lived it. I had dedicated myself to a life of ministry. I was a “doer of the Word, not a hearer only.” I had lived by faith, putting my life, health and future on the line—how many “true believers” have done that? I prayed, spoke in tongues and “sang in the spirit.” I searched the scriptures for guidance. I knew that Jesus was my friend, lord and savior, and I had a daily inner dialogue with him, asking for help and praising him for his blessings. I had brought people to faith in Jesus and had seen many converts. I had heard countless testimonies of believers who told me they felt the “spirit of God” on my ministry (unless they were not true Christians either). There are people in the ministry today who credit me with helping to inspire them to preach and become ministers. I was invited and re-invited to minister in hundreds of Christian churches. How many “true Christians” can say they have done as much?
The reason I rejected Christianity was not because I did not understand or experience it. It wasn’t because I despised God or hated the Christian life. I loved what I was doing and never imagined throwing it away.
If I was not a true Christian, then nobody is.