Jesus taught them that His Kingdom was not of this world, it was not a physical kingdom but a spiritual one.

Jesus answered, "My kingdom is not of this world. If my kingdom were of this world, my servants would have been fighting, that I might not be delivered over to the Jews. But my kingdom is not from the world." John 18:36 ESV

What this is saying is "If My kingdom were of this world, and it is not, then My servants would be fighting, which they are not."

Jesus is a King and He has a kingdom, but His "kingdom" was not the type of kingdom that would compete with Caesar's kingdom by waging war. Jesus is no political revolutionary: His kingdom is not of this world.

Jesus is saying in very plain words that His Kingdom is not a physical, geographic, Kingdom. His Kingdom is spiritual, it is other worldly, it is not of this (physical) realm.

Being asked by the Pharisees when the kingdom of God would come, he answered them, "The kingdom of God is not coming in ways that can be observed, nor will they say, 'Look, here it is!' or 'There!' for behold, the kingdom of God is in the midst of you." Luke 17:20-21 ESV

Jesus taught that His Kingdom is a spiritual Kingdom. Yet, despite the clear words of Jesus, many are looking for a physical Kingdom. His Kingdom is here now, it was consummated in A.D. 70, it is a spiritual Kingdom, not a physical fleshly kingdom, and it did not come with observation.

Matthew teaches us much about the Kingdom of Heaven. Thirty two times in Matthew's Gospel Jesus talks about the Kingdom of Heaven. Matthew's dominating idea is that of Jesus as the Messiah and King of Israel.

Jesus spoke Hebrew; the Gospel writers translated Jesus' sermons and parables into Greek. Mark, Luke, and John translated Jesus' words as "Kingdom of God." Matthew sometimes used this phrase too, but often he preferred to translate Jesus' Hebrew words as "Kingdom of heaven." The two phrases mean exactly the same thing, because they are translations of the same Hebrew words of Jesus.

What did Jesus mean when He spoke of the Kingdom of God? He meant, quite simply, the rule of God. The Kingdom of God is the reign of God. Matthew emphasizes the coming Kingdom and the judgment of all who reject it. Right at the beginning, there is John the Baptist's call to repentance and warning of judgment to all who rejected God's Kingdom.

Adapted in part from David Curtis