My son was raised in a Christian home, went to Lutheran grade school, high school and college. He has now rejected Jesus and is practicing Judaism. He says there is no hell, no salvation. Life is about making the world a better place. I know praying is the most powerful thing I can do, but I don't even know what to say to him or how to approach him about this.
Yes, continue to pray for your son; I will do the same. Also, continue to be a Christian influence in his life. Godly examples reinforce Christian witnessing, and your son needs both. See what you and others in your family and circle of friends might do to keep the gospel of Christ in your son’s life. It could be simple things like emails or text messages that contain Bible passages. We never know what God might do with those things.
As far as approaching your son about this change in his life, you can determine what to say to him by asking him questions. You might think of pursuing questions like these: When did he start having second thoughts about Jesus and the Christian faith? Were there any circumstances or events in his life that led to questioning his faith? Were there influential people in his life who played a role in his embracing Judaism? What finally led him to reject Jesus and the Christian faith?
I wonder also if one of our pastors is in a position to speak to your son. If that is an option, please consider that route.
We know that God changes hearts through his powerful gospel (Romans 1:16). At some point, it would be good for your son to read through the book of Hebrews. That book clearly and repeatedly shows how Jesus Christ is far superior to anything associated with Judaism. You and I won’t be able to convince your son of that truth, but the Holy Spirit can.
Finally, use your pastor as a resource person. Explain to him what you learn about your son’s change of heart and see how he might be able to assist you in future conversations with your son.
It certainly sounds like you did what you could as a Christian parent: raising your son in a Christian environment and enabling him to receive a Christian education for many years. Your son is responsible for the life he is now leading. Like the father in the parable of the lost son (Luke 15:11-32), you stand ready and willing to receive your son back into the fold of God’s family. God shares that same attitude. God bless all that you and others do for your son, that he may again confess Jesus as Savior and enjoy every blessing won by his holy life and sacrificial death.