What is the Kingdom of Heaven?
The “Kingdom of Heaven” (מַלְכוּת הַשָׁמָיִם, malchut hashamaim) is an ancient Jewish idea easily traced back to the Hebrew Bible, where the prophets speak of a coming messianic age when God will establish His kingdom on earth. Isaiah prophesied that “the government will be upon” Messiah’s shoulder “and His name will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace” (Isaiah 9:6). In reality, God was always supposed to be the king (מֶלֶךְ, melech) of Israel, but in 1 Sam 8:7, he says to Samuel, his servant, “they have rejected Me from being King over them.” A sad state of affairs. Yet many Hebrew prophets still look to the day when Israel and the whole world will be ruled by Hashem himself, “And the YHVH (יהוה, Adonai) will be King over all the earth; on that day the Lord will be the only one, and His name the only one” (Zech 14:19).
The kingdom (מַלְכוּת, malchut) must have a proper ruler (מֶלֶךְ, melech). In Jewish thinking, this sovereign reign of God on earth is understood as the future. The LORD (יהוה, Adonai) will be king. And yet a measure of this spiritual reality of God's reign can be experienced at any moment, and that is the broader idea of the “Kingdom of Heaven” (מַלְכוּת הַשָׁמָיִם, malchut hashamaim) we encounter on the pages of the Jewish gospels in particular.