1. Kingdom of God: Proclamation that Jesus is the Christ (Acts 1:3)
    Isa 9:1-3,6-7, Isa 35:5-10, Dan 2:44-45, Mt 12:28, Lk 24:45-47)

The Old Testament prophesied that the kingdom of God would be established when Christ came to this earth. (Isa 9:1-3,6-7, Isa 35:5-10, Dan 2:44-45)

Isa 9:1 Nevertheless the dimness shall not be such as was in her vexation, when at the first he lightly afflicted the land of Zebulun and the land of Naphtali, and afterward did more grievously afflict her by the way of the sea, beyond Jordan, in Galilee of the nations.
2 The people that walked in darkness have seen a great light: they that dwell in the land of the shadow of death, upon them hath the light shined.
3 Thou hast multiplied the nation, and not increased the joy: they joy before thee according to the joy in harvest, and as men rejoice when they divide the spoil.
6 For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.
7 Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the Lord of hosts will perform this.

Isa 35:5 Then the eyes of the blind shall be opened, and the ears of the deaf shall be unstopped.
6 Then shall the lame man leap as an hart, and the tongue of the dumb sing: for in the wilderness shall waters break out, and streams in the desert.
7 And the parched ground shall become a pool, and the thirsty land springs of water: in the habitation of dragons, where each lay, shall be grass with reeds and rushes.
8 And an highway shall be there, and a way, and it shall be called The way of holiness; the unclean shall not pass over it; but it shall be for those: the wayfaring men, though fools, shall not err therein.
9 No lion shall be there, nor any ravenous beast shall go up thereon, it shall not be found there; but the redeemed shall walk there:
10 And the ransomed of the Lord shall return, and come to Zion with songs and everlasting joy upon their heads: they shall obtain joy and gladness, and sorrow and sighing shall flee away.

Dan 2:44 And in the days of these kings shall the God of heaven set up a kingdom, which shall never be destroyed: and the kingdom shall not be left to other people, but it shall break in pieces and consume all these kingdoms, and it shall stand for ever.
45 Forasmuch as thou sawest that the stone was cut out of the mountain without hands, and that it brake in pieces the iron, the brass, the clay, the silver, and the gold; the great God hath made known to the king what shall come to pass hereafter: and the dream is certain, and the interpretation thereof sure.

It is the kingdom of God that is proclaimed and acknowledged by men that Jesus is the Christ. Jesus taught the kingdom of God by explaining the Old Testament. (Acts 1:3, Lk 24:45-47)

Acts 1:3 To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:

Lk 24:45 Then opened he their understanding, that they might understand the scriptures,
46 And said unto them, Thus it is written, and thus it behooved Christ to suffer, and to rise from the dead the third day:
47 And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.

The kingdom of God began with the coming of Jesus. (Mt 12:28)

Mt 12:28 But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you.