Kingdom of Heaven (Greek: βασιλεία τῶν οὐρανῶν) is a term used in the Gospel of Matthew in preference to the "kingdom of God" (Greek: βασιλεία τοῦ θεοῦ) of the Gospel of Mark and the Gospel of Luke, thought to be the main content of Jesus's preaching, described by Edward Schillebeeckx as referring to "a process, a course of events, whereby God begins to govern or to act as king or Lord, an action, therefore, by which God manifests his being-God in the world of men".
Clarke notes that Matthew 3:2 is the first of twenty-nine references to the "Kingdom of Heaven" in the Gospel of Matthew. The gospels of Luke and Mark tend to prefer the term "kingdom of God." That Matthew uses the word heaven is often seen as a reflection of the sensibilities of the Jewish audience this gospel was directed to, and thus tried to avoid the word God. Most scholars feel the two phrases are theologically identical. Robert Foster rejects this view. He finds the standard explanation hard to believe as Matthew uses the word God many other times and even uses the phrase Kingdom of God four times. Foster argues that to Matthew the two concepts were different. He feels that the word heaven had an important role in Matthew's theology and links the phrase especially to Father in Heaven, which Matthew frequently uses to refer to God. Foster argues that the Kingdom of God represents the earthly domain that Jesus' opponents such as Pharisees thought they resided in, while the Kingdom of Heaven represents the truer spiritual domain of Jesus and his disciples.
Scholars believe that when it was originally written this phrase was intended to be eschatological with the Kingdom of Heaven referring to the end times. When the last judgment failed to occur Christian scholars gradually redefined the term to refer to a spiritual state within, or worked to justify a much delayed end time. This passage presents a difficulty in this later endeavour as the phrase translated as "at hand" or "is near" both refer to an imminent event. Albright and Mann suggest better translation would state that the kingdom is "fast approaching."R. T. France sees it as even more immediate suggesting that the phrase should be read as referring to "a state of affairs that is already beginning and demands immediate action."