Repentance is of central importance because sin brings God's judgment and fellowship with God is only possible through full and sincere repentance. God, through his servants, calls people to repent as the only way to escape the judgment and receive the forgiveness and restoration which he offers.
Repentance may not remove the effects of human sin
Numbers 14:39-45The Israelites' repentance could not prevent the wandering that resulted from their refusal to enter the promised land; 1 Samuel 15:24-26Saul's repentance is too late to escape God's judgment on his kingship; 2 Samuel 12:13-14Despite David's repentance the son of his adulterous relationship with Bathsheba still died; Hebrews 12:16-17Esau's repentance could not bring back the birthright he had sold to Jacob.