Matthew defines for his audience what he means by the phrase “kingdom of heaven”.
Jesus was going throughout all Galilee, teaching in their synagogues and proclaiming the gospel of the kingdom, and healing every kind of disease and every kind of sickness among the people. ( Matt. 4.23) NASB
After reading in Matt. 4.17, that Jesus began to preach the kingdom of heaven, Matthew defines what the kingdom of heaven actually is. According to Matthew, what Jesus was preaching and teaching was the kingdom of heaven as gospel. The kingdom of heaven is not a code phrase for going to heaven as some might think. Rather the kingdom of heaven is synonymous with the kingdom of God (see article on Matt. 4.17). How Matthew defines kingdom of heaven is by calling it gospel or good news. The good news is the kingdom. There are two aspects to the kingdom of heaven or God, and that is a present aspect and a future aspect. Matthew 4.23, shows the present aspect of the kingdom. Verse 4.23 and 24 tell us about all sorts of people coming from all over the area just to see Jesus and be healed. Jesus brought a piece or a glimpse of the kingdom with him in the present. Hebrews 6.5 helps explain this further. In verse 4 the author talks about those who have been enlightened and have tasted the heavenly gift and partakes of the Holy Spirit, which Jesus fits into that category. Verse 5 says that they have tasted the word of God (the New Testament definition for ‘the word of God’ not the Bible, rather the gospel) and the powers of the age to come. Jesus brought with him in his ministry the powers of the age to come, we saw this through his ability to forgive, heal the sick, raise the dead, and preforms miracles. Jesus was preaching and teaching in the synagogues this gospel of the kingdom continuously. The kingdom message has power for people now, as we see in Jesus’ ministry to those who believed it.