Repentance is the foundation of the gospel message. God commissioned John the Baptist to prepare the Lord's way, and he preached "Repent, for the kingdom of heaven is at hand" along with a baptism of repentance for the remission of sins. Jesus began with the same words, adding "Repent, and believe the gospel," and said He came to call sinners to repentance, not the righteous. After His resurrection He told His disciples that repentance and remission of sins must be preached in His name to all nations, beginning at Jerusalem. Paul likewise told the Athenians that God now commands all men everywhere to repent, because He has appointed a day to judge the world in righteousness. Paul also testified that he preached repentance, turning to God, and performing works appropriate to repentance everywhere he went (Acts 26:20). Mainstream Christianity has pushed repentance into the shadows, emphasizing accepting Jesus and believing God forgives all sins. Yet neither genuine baptism, nor remission of sins, nor genuine acceptance of Christ as Savior can occur until a person repents. The Greek words metanoeo and metanoia denote a radical, moral turn of the whole person away from sin and to God, not merely feeling sorry. Translations of Paul's words, such as "deeds in keeping with their repentance" and "prove their repentance by their deeds," agree that real repentance always includes a change in behavior, which requires individual exertion. Repentance is also a critical issue for the end-time church.

Jesus commands His church to preach the gospel to all the world, but the reason for preaching determines whether the church is in harmony with God. Nominal Christianity preaches to save the world and bring everyone into the church, yet no one can come to Christ unless the Father draws him (John 6:44, 65), and salvation is not now open to everyone. God calls only a small, elect "little flock," as the narrow gate and the Parable of the Sower show. The clearest statement of purpose is Mark 1:14-15, where Jesus preaches, "Repent, and believe in the gospel." The gospel is a warning message calling people to turn from sin because God's Kingdom will soon be established and He will render to each according to his deeds (Romans 2:6). Preaching is a witness, testifying to who God is, what His standards are, what He is doing, and what is coming, so that humanity has no excuse when He brings destruction on this world and establishes His Kingdom. From those who hear, God chooses a few to respond in repentance and belief and enter the church, where He teaches them to observe all that Christ commanded. Most of mankind will have opportunity for repentance and salvation in the second resurrection, since God is not willing that any perish but that all come to repentance (II Peter 3:9). In this age, preaching warns the world and trains the few.

The Two Witnesses will give this world one final warning, a message of rebuke and repentance, during the 3 1/2 years just before Christ's return. They are two human beings of that time, not Moses and Elijah resurrected, because God always uses people of the time to carry out His work. He has never raised a prophet or apostle to do a work centuries or millennia later. God gives them extraordinary power to carry out their ministry. Fire proceeds from their mouths to devour anyone who tries to harm them before they finish, as with Elijah. They can also produce drought and famine, and strike the earth with plagues, as Moses did. Their call to repent will bring them into conflict with the people and governments in power, and they will be martyred. The world will rejoice over their bodies in the streets of Jerusalem, but great fear will seize those same people when the Witnesses come to life and ascend in a cloud. Their preaching also reaches inward. As the two olive trees and two lampstands, they supply the church with oil, spiritually feeding it during the famine of the Word, so they will be affiliated with and teaching God's church before and possibly during their worldwide ministry.