The kingdom of heaven is Matthew’s customary expression for the kingdom of God. At the time of writing, God’s name was considered too holy to mention, with the result that heaven
was used as a euphemism for God (Matthew 19:23; Matthew 10:23). 1 The kingdom in view, is not the universal kingdom over which God reigns (for example, the whole world), but a subset (believers who belong to God and will be part of the new creation). With the coming of Christ, this kingdom has drawn near (Matthew 4:17). The promised King has come and he is beginning to inaugurate the new heavens and earth.
3 “Blessed are the poor in spirit, for theirs is the kingdom of heaven.