* Matthew 4:23 - "And Jesus went about all Galilee, teaching in their synagogues, and preaching the Gospel of the kingdom, and healing all manner of sickness and all manner of disease among the people."
* Matthew 9:35 - "And Jesus went about all the cities and villages, teaching in their synagogues, and preaching the Gospel of the kingdom, and healing every sickness and every disease among the people."
* Matthew 24:14 - "And this Gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come."
* Mark 1:14-15 - "Now after that John was put in prison, Jesus came into Galilee, preaching the Gospel of the kingdom of God, and saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the Gospel."
Another question arises when biblical scholars teach that the kingdom of God and the kingdom of heaven are two different kingdoms. But in order to believe that, one must separate the Gospel of Matthew's teaching on the kingdoms from the rest of the New Testament. That is because only Matthew's Gospel used the term "the kingdom of heaven." He used "kingdom of heaven" thirty-one times (3:2; 4:17; 5:3, 10, 19, 20; 7:21; 8:11; 10:7; 11:11, 12; 13:11, 24, 31, 33, 44, 45, 47, 52; 16:19; 18:1, 3, 4, 23; 19:14). To complicate the issue, we see that Matthew also used the term "kingdom of God" five times (Mt. 6:33; 12:28; 19:24; 21:31; 21:43).
Another problem with believing that there are two different kingdoms, is that Mark's and Luke's Gospels record the Lord's words in parallel passages as "the kingdom of God" (Mt. 4:17 w/ Mk. 1:15; Mt. 5:3, 10 w/ Lk. 6:20, 22; Mt. 8:11 w/ Lk. 13:28; Mt. 10 7 w/ Lk. 9:60; Mt. 11:11 w/ Lk. 7:28; Mt. 11:12 w/ Lk. 16:16; Mt. 13:11 w/ Mk. 4:11; Mt. 13:31 w/ Mk. 4:30-31; Mt. 13:33 w/ Lk. 13:20-21; Mt. 19:14 w/ Mk. 10:14; Mt. 19:23 w/ Mk. 10:23; Mt. 25:14 w/ Lk. 19:11-13)!
I suppose that some Bible students have sort of gone "overboard" when it comes to "rightly dividing the Word of truth" (2 Tim. 2:15). And while I have your attention, may I say that it is quite possible that I am wrong, as some great men of faith have understood this topic differently; men such as John Walvoord, Charles Ryrie, and C.I. Scofield. I guess when it comes right down to the "nitty-gritty," it all belongs to God! Praise Him for keeping us humble, lest we think more highly of ourself as we ought!
Bottom line: Believe in Jesus Christ and you will enjoy His kingdom forever!