Was the kingdom of God inside those Jesus was talking to? It says Jesus was talking to a group of hostile Pharisees. Which is why, pretty consistently, it is understood that Jesus was directing their focus to Himself, and why many translations render this as "in your midst" rather than "within you". That is, the kingdom was present right before them, in the Person of Jesus Himself. And it continues to be here through the Church, which is why Christ says we must be born again, i.e. born of water and the Spirit to enter the kingdom. All who are baptized are members and citizens of God's kingdom, since Christ rules from heaven through His Church--not as a secular king who orders violence and invasion and force, because if we pay attention to what Christ says, He is clear that God's kingdom is not like the kingdoms of this world. The way God is King is through the Cross. We behold what God's kingdom looks like in the suffering, death, and resurrection of Jesus. It is where the last is first, the least is greatest, where "the greatest among you is your slave", where the poor, the hungry, and the downtrodden are blessed. So when Christ the King reigns through His Church it is not with a sword against nations, it is as the Servant who administers peace to the broken and medicine to the sick.
One day, which only the Father knows, our Lord will return, in glory, as judge of the living and the dead, and the fullness of the kingdom shall come with Him, all things will be given over to the Father, and God will be all in all. And there will be world without end, life everlasting, and the hope of all the ancient prophets fulfilled: a new heavens and a new earth, all the former things are gone, and all is made new.
"They shall not hurt or destroy in all my holy mountain; for the earth shall be full of the knowledge of the LORD as the waters cover the sea." -Isaiah 11:9
-CryptoLutheran