What is the meaning of “grace upon grace” in John 1:16? If an unbeliever is a slave to sin, how can he ever come to Christ? My friend thinks we believers can sin enough to harden our heart and walk away from Jesus. How do I respond to this?

Tags: call upon the Lord, Calvinism, Ephesians 6:24, grace upon grace, hardened heart, John 1:16, new heart, saved, slave to sin, undying love