The Old Testament uses the word "the Kingdom" 236 times, and the New Testament 163 times. With very few exceptions, they all have to do with earthly kingdoms. In the beginning, God created Adam and said he was to have dominion over the earth (Gen. 1:26-28). Sort of like Esau selling his birthright for some pottage (Gen. 25:29-34), Adam ceased to have dominion, giving it to Satan; we are told that Satan is now the god of this world (2 Cor. 4:4).
Nearly 2000 years later, God chose Abraham to begin an earthly nation (Gen. 12:1-2). After about another 500 years, God told Moses to write: "And I will walk among you, and will be your God, and ye shall be My people" (Lev. 26:12). You would think that would satisfy Israel, but no, they rejected God as their authority, and, wanting to be like the other nations, they demanded to have their own king (1 Sam. 8:5-22). God had Samuel anoint Saul, and his successor, David to be kings over Israel (1 Sam. 10:1; 16:13). God told Samuel that David's kingdom would last forever (2 Sam. 7:16).
After centuries of being enslaved by Gentile empires, the Jews longed for their King, their Christ, their Messiah, to come and fulfill the promise that David's kingdom would last forever. When Jesus came, both His friends and His enemies recognized Him as the One for whom they waited (Mt.16:16; Jn. 1:45; 20:28; Mk. 1:34; 3:11; Lk. 4:41; etc.). Even at His Ascension, the disciples were still looking for Him to establish His earthly kingdom (Acts 1:6). But the Kingdom of God will not occur until after the Tribulation; it will begin at Christ's Second Coming (Mt. 24:29; Rev. 19:11 - 21:1). The Church, having been removed from the earth via the Rapture (Jn. 14:1-3; 1 Thes. 4:13-18), will return with Him to rule the long-awaited Kingdom of God (1 Cor. 6:1-3; 2 Tim. 2:12; Rev. 2:26-27; 20:6)! The Church is not the Kingdom, but by His grace, it will be there!
If you want to see the kingdom, you have to believe in the King!