Surrender.  That's what it takes.  Some say it is belief in Jesus, but the Devil himself believes in Jesus.

Speaking of the devil,  James the brother of Jesus put it this way:   James 2: 19  "You believe in God; you do well: the devils also believe, and tremble."

The devil tempted Jesus and mocked him saying:  Matthew 4:3b, 6a  "If you are the Son of God, command that these stones be made bread."   "If you are the Son of God,  jump off this building."

Jesus answered, "You shall not tempt the Lord...."

So if it isn't simple belief, what is it?  It is belief and faith, but also surrendering to the will of God.  We don't want to do that.  We want to run the show.  Yes, you have to believe that Jesus is the Son of God and that he rose from the dead.  But he must be Lord.  Of all.   You must give yourself to him.

Galatians 2:20  "I am crucified with Christ; nevertheless I live; yet not I, but Christ lives in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for  me."  The only thing about life here on earth that counts is the life of Christ living within you.  That is the kind of life that is eternal.

Dietrich Bonhoeffer said, "Christ bids a man to come and die."  That self will, that part of you that says, "I want what I want,"  must become "I want what You want."  We must crucify our self will.   Then you know that you belong to God and that no one can pluck you out of his hand.

Believe that Jesus is the Son of God and that He rose from the dead.  Admit that you are a sinner and that no matter what you do you can't get rid of your guilt.  Repent. (That doesn't mean being sorry)  Repentance means:  With Your help, I will never turn back to those old behaviors.  I will do a one eighty turn.  Give him your life.  You won't be sorry.  It works better that way.