Jesus reveals that sin keeps one out of heaven (John 8:21, 24); specifically the sin of unbelief that He is the promised Messiah (cf. John 16:8-9). When one comes to faith in Christ, he/she is forgiven of all their sins (Eph. 1:7; Col. 1:13-14), past, present, and future (Heb. 10:10-14).  Forgiveness is first judicial, removing the penalty of sin (John 3:18; 5:24; Rom. 8:1; 8:33-34).  Forgiveness is also familial, restoring fellowship with God after we’ve sinned (1 John 1:5-10; cf. Ps. 32:1-5).