The kingdom of God, or the kingdom of heaven, is a central theme of Jesus' teaching. Although the two phrases are generally interchangeable, Matthew, who wrote primarily for a Jewish readership, tended to use the phrase "the kingdom of heaven," while Mark and Luke, who both wrote for basically Gentile audiences use "the kingdom of God," which is would be understood more easily by non-Jews. Because the Jewish people so deeply respected the name of God and therefore tended not to speak it lest they use it lightly, they responded more readily to the expression "kingdom of heaven." The meanings, however, are identical.

John the Baptist announced that the kingdom was at hand. This indicated to the people that a dramatic intervention by God into the affairs of men would restore the nation of Israel and free them from outside rulers. According to popular expectations, the Messiah-the Anointed One of God-would be the person who would deliver them from oppression and then establish the kingdom.

Jesus endorsed John's teachings and added further insights. Although he also spoke of the judgment to come and the need for repentance, he stressed the saving nature of the kingdom for those who entered it. He announced that the kingdom was not only a future promise but a present reality in the lives of those who submitted to its demands. In one sense the kingdom of God or heaven is the reign of God in the hearts and lives of people who respond in faith and repentance to him. The "present" aspects of the kingdom showed up in the casting out of demons, in which the kingdom of God overpowered the "kingdom of the evil one."

At the same time, Jesus spoke of the kingdom in a future sense-some time in which the reign of God would be perfected and the powers of evil overthrown. During the interim, until the kingdom and its king come in open glory, the good news of the kingdom should be preached to the ends of the earth and to all peoples and nations.