John the Baptist began preaching, "'Repent, for the kingdom of heaven is at hand'" (Mt 3:2). The purpose of it was "for the forgiveness of sins" (Mk 1:4). It is because "all have sinned and fall short of the glory of God" (Ro 3:23). Then "Jesus came into Galilee, preaching the gospel of God, and saying, 'The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel'" (Mk 1:14-15). Paul said, "Having overlooked the times of ignorance, God is now declaring to men that all people everywhere should repent'" (Ac 17:30). Isaiah said to "turn from transgression" (Isa 59:20) and Ezekiel said to tell him to "turn from his wickedness or from his wicked way" (Eze 3:19). Paul said "the Lord will . . . bring to an end . . . the activity of Satan . . . with all the deception of wickedness for those who perish, because they did not receive the love of the truth to be saved" (2Th 2:8-10). The disciples told Jesus about the Galileans who Pilate had killed. He replied, "'Unless you repent, you will all likewise perish'" (Lk 13:3). To perish means to die or be destroyed. God said to Ezekiel, "'Warn the wicked from his wicked way that he may live'" (Eze 3:18). Jesus said, "'Whoever believes in Him shall not perish, but have eternal life'" (Jn 3:16). Also, "'I give eternal life to them, and they will never perish'" (10:28). The Lord is "patient toward you, not wishing for any to perish but for all to come to repentance" (2Pe 3:9). "Do you not think . . . that the kindness of God leads you to repentance?" (Ro 2:4). "The sorrow that is according to the will of God produces a repentance without regret, leading to salvation" (2Co 6:10). It is "repentance toward God" (Ac 20:21).
How would you answer a person who asked, "Why would I have to repent if I didn't sin like Adam?" (Ro 5:14). Adam sinned because he broke God's commandment (Ge 2:17). He disobeyed (even rebelled) because he was not deceived (1Ti 2:14). Perhaps he ate the fruit Eve gave him because he just wanted to keep her happy. Maybe he rationalized that death would be only a temporary disciplinary action. It's possible he considered knowing more and becoming wiser would be worth it. "Through the one man's disobedience the many were made sinners" (Ro 5:19). It's as though we, as descendants, have inherited the "original sin." Since "by a man came death" (1Co 5:21), through solidarity with Adam, "death spread to all men, because all sinned" (Ro 5:12). "Like Adam they have transgressed the covenant" (Hosea 6:7). Our guilt is imputed in a legal way as if a contract has been violated and a judgment has taken place because the ground has been cursed (Ge 3:17-18). This is the Adamic Covenant where Adam, as the representative of the human race, causes God to introduce physical death saying, "'You [will] return to the ground, because from it you were taken'" (:19). Others may say that Adam's nature became corrupted by the sin and that we inherit the corruption and sin automatically (Ro 5:19). Calvinists believe that we are incapable of being spiritually saved except for God's grace. So if you repent for these reasons you acknowledge that "through the obedience of the One the many will be made righteous" (:19).