What was it that changed your heart from unbelief to faith in Jesus? It's remarkable to ask Christians that question and see how eager they are to give God the glory, not self. Which is a very good instinct. As John Piper says, "There is something about true grace in the believer's heart that makes us want to give all glory to God." Many of us have discovered that sometimes our experience of the power of God's grace far outpaces our theological explanation of it.
John Newton, author of "Amazing Grace," was an awful, evil man whose heart was captured by God. Reflecting on his lifestyle as an unbeliever, he wrote, “I not only sinned with a high hand myself, but made it my study to tempt and seduce others upon every occasion: nay I eagerly sought occasion sometimes to my own hazard and hurt” (Memoirs, 13). Newton is one of many examples that God’s strength is able to overcome all stubbornness and depravity.
As I wrestled with Calvinism, I was confronted with this dilemma and tension. I had already accepted that man is totally depraved based on what I read in the Scriptures, and because I knew (too well) the state of my own heart and my own failures.
What made me believe? Who gave me sight? I can’t take credit for my salvation just as Lazarus can't take credit for his resurrection. Like Newton, I knew I had been evil — spiritually dead in sin since physical birth. But something changed inside of me. I think most Christians, if pressed with this question, would acknowledge that something miraculous happened to them. God is glorified when his grace alone is credited for our salvation.