A lot of Christians are surprised you tell them that what we call the beatitudes from the Sermon on the Mount listed in Matthew 5 were not written to the New Testament Church found in the body of Christ. Far from it, the Sermon on the Mount is Jesus telling the Jews about what life will be like in the Millennium when He returns as King to sit on the throne of David and rule over the whole Earth for a thousand years. But even though it was not written to us as doctrine, there is a boatload of doctrinal dynamite contained in these 9 beatitudes given by the Lord, and we would do well to rightly divide and understand them.
"And seeing the multitudes, he went up into a mountain: and when he was set, his disciples came unto him: And he opened his mouth, and taught them, saying, Blessed are the poor in spirit: for theirs is the kingdom of heaven." Matthew 5:1-3 (KJB)
The Sermon on the Mount and the 9 beatitudes, or blessings, contained therein are actually the foundational pillars that comprise the 'Constitution of the Kingdom of Heaven' that Jesus will rule and reign over. The blessings mentioned in the Sermon on the Mount constitute what life will be like during that time period, it is a constitution of that kingdom as prophesied in the Old Testament. It is not doctrine for Church Age believers, but a wonderful promise of what is to come when King Jesus is ruling in perfect righteousness.