Repent: for the kingdom of heaven is at hand. (Matthew 4:17)

This appears to be the first teaching of Jesus following his baptism and his 40-days fasting and his temptation. What does it mean? And why did he start his ministry by repeating the central theme of the teachings of John the Baptist?

Jesus vindicated John the Baptist by continuing his very teachings at the very beginning of his ministry.

1 In those days came John the Baptist, preaching in the wilderness of Judaea,

2 And saying, Repent ye: for the kingdom of heaven is at hand. (Matthew 3:1-2)

It was also a way to appeal to the followers of John, so that they, by and by, would realize that Jesus truly was the one whom John was preparing the way for. John himself had done great things to proclaim the Messiah-ship of Jesus:

26 John answered them, saying, I baptize with water: but there standeth one among you, whom ye know not;

27 He it is, who coming after me is preferred before me, whose shoe's latchet I am not worthy to unloose.

28 These things were done in Bethabara beyond Jordan, where John was baptizing.

29 The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world.

30 This is he of whom I said, After me cometh a man which is preferred before me: for he was before me.

31 And I knew him not: but that he should be made manifest to Israel, therefore am I come baptizing with water.

32 And John bare record, saying, I saw the Spirit descending from heaven like a dove, and it abode upon him.

33 And I knew him not: but he that sent me to baptize with water, the same said unto me, Upon whom thou shalt see the Spirit descending, and remaining on him, the same is he which baptizeth with the Holy Ghost.

34 And I saw, and bare record that this is the Son of God.

35 Again the next day after John stood, and two of his disciples;

36 And looking upon Jesus as he walked, he saith, Behold the Lamb of God!

37 And the two disciples heard him speak, and they followed Jesus.

38 Then Jesus turned, and saw them following, and saith unto them, What seek ye? They said unto him, Rabbi, (which is to say, being interpreted, Master,) where dwellest thou?

39 He saith unto them, Come and see. They came and saw where he dwelt, and abode with him that day: for it was about the tenth hour.

40 One of the two which heard John speak, and followed him, was Andrew, Simon Peter's brother.

41 He first findeth his own brother Simon, and saith unto him, We have found the Messias, which is, being interpreted, the Christ.

42 And he brought him to Jesus. And when Jesus beheld him, he said, Thou art Simon the son of Jona: thou shalt be called Cephas, which is by interpretation, A stone. (John 1:26-42)

So, John's transfer of power to Jesus had the effect that Jesus' senior Apostle was called, and at least one more Apostle. What a wonderful thing for John, to see his own disciples pick up and follow the Messiah, but at the same time it might have been with a bit of sadness that he understood that his time of service was drawing to a close. How great it must have been to hear the Messiah continue proclaiming his words, giving proof to him that he had truly taught the words of God.

The Kingdom of Heaven has always been at hand! For the righteous person who dies, who has received the saving ordinance of baptism, will enter into the Heavenly Kingdom of God. That kingdom is actually situated in Heaven, and has always been. Why, then, did John and Jesus preach it as a new thing that the Kingdom of Heaven was at hand?

The fully organized Church of Jesus Christ is the Kingdom of Heaven on the earth. This means that John the Baptist and Jesus, as they were proclaiming that "the Kingdom of Heaven is at hand" were prophesying that the true Church of Jesus Christ was about to be organized. And true enough, not long after it was, as the Apostles were given the "keys of the Kingdom of Heaven:

19 And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven. (Matthew 16:19)