Note 77 at Jn. 16:9: The sin that the Holy Spirit is reproving the world of is the sin of not believing on Jesus. All other acts of sin stem from this one problem. That's the sin that will send men to hell -- not their individual acts. All the sins of the world have been paid for (1 Jn. 2:2) except the sin of rejecting Jesus (Jn. 3:18).