Here’s a bit lengthy but worthy quote:
Why don’t people come to Jesus? At one level the answer is because they “refuse to come.” In other words, people do not want to come. Some call this the choice of free will. Jesus would probably say it is the choice of a will enslaved to sin. “Truly, truly, I say to you, everyone who commits sin is a slave to sin” (John 8:34). Jesus would say that people do not come to him because they are enslaved to their supreme preference for other things. “The light has come into the world, and people loved the darkness rather than the light…everyone who does wicked things hates the light and does not come to the light” (John 3:19-20).
How then has anyone ever come, since we are all enslaved to sin and spiritually dead? Jesus’ answer was that God, in his great mercy, overcomes our resistence and draws us: “No one can come to me unless the Father who sent me draws him” (John 6:44). “No one can come to me unless it is granted him by the Father” (John 6:65). God grants the gift of new birth and repentance, which opens the eyes of the spiritually blind to the truth and beauty of Jesus. When this happens, all suicidal objections fall. We are finally free. And, finally free from slavery, we come.
When you come to Jesus like this, you will never cease to praise and thank him for his sovereign grace [John Piper, What Jesus Demands from the World (Wheaton: Crossway Books, 2006), 46-47].