1 John 5:16 supports the non-Calvinist view. What is the sin that leads to death? Only one, rejecting the work of the Holy Spirit in the birth, life, miracles, death and resurrection of Jesus. He that does not believe is condemned already. What are we not to pray for? The man? Nope. We are not to pray that God would forgive this sin and allow a non-believer into heaven, but we can pray that God would use us to help the man change his mind, and accept the gospel for we are to pray for the lost such as Paul's prayer of Romans 10:1. God's desire is for all men to be saved so we are to pray in the will of God that all men will be saved according to God's purpose, saved in a way that glorifies God, which is by their autonomous response to message of the Gospel brought by word and example of Spirit led believers bringing mercy to the lost. We are ambassadors of Christ and we have the ministry of reconciliation. We are to pray for more workers because the harvest is plentiful.