Except a man be born again, he cannot see the kingdom of God. John 3:3.
A great many people who in the past have come to Christ think they must not have really come, because the surrender didn't last. That's one of the big dilemmas in the Christian world today. There are hundreds of people who have sincerely come to Jesus with a great sense of need and have later become disenchanted when the "conversion" seemed to fade away. It is possible to have genuinely accepted Christ and given up on self during the Week of Prayer last school year or on the sawdust trail forty years ago, but to have the commitment die from doing nothing about it ever since. In order to grow in the Christian life we must learn how to be converted every day.
Conversion is more than saying Yes to God one time. When someone wakes up the week after the week before and discovers that he still has some of the same problems, weaknesses, and fears, he is tempted to think it must not have really "happened" after all. And he waits for the next revival or camp meeting or altar call to run it by again. He does not realize that often the devil works harder when he sees someone come to Christ than he ever did before. Things may go worse for a period of time after conversions than they did before. There may by more trials, more temptations, and more defeats than before the decision was made. Have you seen it happen? The devil tries everything he knows to get us to give up and forget about God.
If conversion is not immediate victory, peace, and freedom from temptation and trial, what is it? Here is a definition of conversion, based on two chapters in The Desire of Ages, "Nicodemus" and "At Jacob's Well": Conversion is a supernatural work of the Holy Spirit upon the human heart, producing a change of attitude toward God and creating a new capacity for knowing God that we didn't even have before.
Conversion is God's work, never ours. When we are born again, instead of being against God, we're now on His side. And we then have a relish for spiritual things that were foolishness to us while we were at enmity with God. It is not the end, any more than physical birth is the end of physical life. It is only the equipment to get started. It is only the beginning.