I would say that even as a young child I believed in God and that He was creator. I was given a little New Testament at the age of 6 that I loved even though I couldn't understand it. I have always believed the bible to be the word of God.
I was a God seeker from childhood, but was not raised in a Christian home or taught about God. I did hear His name taken in vain many times. I believe God took mercy on a little ignorant child.
Now that I am saved and have studied the bible for many years, I see how absolutely amazing it is that it even exists. People for thousands of years have tried to rid the world of it, but never succeeded. The fact that it was written over a period of 1600 years by 40 different authors from kings to fishermen, living on different continents, containing only one theme, the Lord Jesus Christ, can only be described as miraculous.
All this lends validity to the bible's authors and I believe their testimony.
Add to that..one day I prayed for God's forgiveness and told Him all I wanted was Him and my life has never been the same. I have a love for scripture that could only be given by God. I does not come from myself. Even through all the ups and downs, the bad churches, bad doctrines and confusion, I cannot let go of Him. I'm either crazy or God really does exist and really does love me. I think it's the latter.