When I started this forum in 2007, I identified myself as a "Bible-believing Christian" in no uncertain terms. For example, here is how I described myself in my old FAQ (which remains on my old site for historical purposes):
Are you a Christian? Protestant? Catholic?
Praise God, I am a man saved by grace through faith in the Lord Jesus Christ (Ephesian 2:8). I am a non-denominational blood-bought Bible-believing Trinitarian Christian. I believe that the true “faith which was once delivered unto the saints” (Jude 3) is well stated in the early creeds of the church that Christ founded.
Likewise, here is my testimony about the purpose of my website on the old homepage:
To this end I labour, to glorify the Triune God; to glorify the Father Almighty, Creator of all, to glorify His Son Jesus Christ my Saviour and Hope, and to glorify the Giver of all divine gifts, my Comforter, Guide, Teacher and Friend, God the Holy Spirit. To You be the glory, thrice holy blessed God of Eternity! To You be the glory, now and forevermore. Amen. Amen. Amen.
And here are the thanks I gave to Christ on my old About page:
I remain eternally grateful to my Lord Jesus Christ, the King of the Universe, for shedding His Light upon me and guiding my path – usually without my knowledge – and giving me both the burning desire and the ability to proclaim the neverending wonders of His Holy Word. Oh! The wonders of His Grace! Had He left me to myself, doubtless I’d be dead or wandering aimless and lost through this dark world. Thank you, my Lord!
So, that's where I was in 2007. How is it possible that I now reject the faith I once believed with such passion? What changed? The answer is really pretty simple. I was "blinded" by the light I saw in the Bible. Anyone who has entered in to the Bible with believing eyes knows how it can capture the soul. It feels alive. It touches chords that resonate down into the deepest parts of ourselves. It is filled with light everywhere you look: the Gospel message shines with its numinous symbolic elements like the Alpha Omega, the Cross, the Dove, the Death and Resurrection of Christ, and on and on it goes. Who wouldn't want to believe such a story? Indeed, the believer wonders how anyone could resist such an amazing Gospel message. And beyond all that, I had the overwhelming witness of the Bible Wheel which seemed to confirm everything about the Bible as the very Word of God. All these thing blinded me to the "dark side" of the Bible. I simply "overlooked" all the problematic passages, errors, contradictions, and moral abominations that didn't fit with the amazingly glorious, and blinding, vision of the Bible as "God's Word."

So here are three of the primary issues that conspired to finally convince me that the traditional Christian faith is not true.

1) The Doctrine of Hell

I cannot conceive of a good God who would design an eternal evil in which souls suffer eternal conscious torment. This is a central doctrine accepted by the vast majority of Christians.

2) The Bible contains many errors, contradictions, logical absurdities, and moral abominations attributed to God.

This point covers a very large class of problems. Many recent threads deal with them. The most significant to me are the moral abominations attributed to God, such as his command to kill all the men, women, and children of people in Canaan.

3) God does not, as a general rule, answer prayers.
This fact seems incontrovertible and it directly contradicts the central promises of the Bible. It was the "final straw" for me.

I would be delighted to dig into these issues with anyone interested.