Every Christian has a story, or should. It is a story of what God had done in their lives.
The man born blind narrative in the Gospel of John, chapter 9, is the best illustration of this principle. The religious leaders of his day wanted to argue theology about Jesus. The blind man never saw Jesus and knew nothing about him, except as he was begging a discussion about why he was born blind arose, someone put mud in his eyes and told him to wash his face, someone named Jesus, and as he washed, he received his sight. The religious leaders tried to discredit the man, but he stood by his story: "I was once blind, but now I see, and the man's name who did this is Jesus."
This is what My God and My Story is all about. Some may want to argue about the existence of God and who Jesus is. They want to want to argue about the Bible, whether or not it is the Word of God or just a book about God. I know God is real. I know Jesus Christ is his only Begotten Son and my Lord and Savior. I know the Holy Spirit is active today.
How do I know? My God and My Story tells how I know. A witness in court can only tell what they have personally seen and heard. All else is considered hearsay. Jesus commanded us as Christians to be his witness. I can only testify to what I have personally seen and heard. It is my story.