If this passage is understood properly, there is no way that Christ would be telling the unsaved Pharisees -- His bitter enemies -- that they had been born again (that the Kingdom of God was within them).
What Christ was teaching them is that while He was on earth, they would not see the Kingdom of God with their naked eyes because it was AN INWARD SPIRITUAL REALITY for those who had believed on Him.
And when he was demanded of the Pharisees, when the kingdom of God should come, he answered them and said, The kingdom of God cometh not with observation:[YOU WILL NOT SEE IT WITH YOUR EYES] Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you. [IF YOU ARE SAVED]
This ties in with John 3:3-7 which teaches us that except a man be born again he can neither see nor enter into the Kingdom of God.
The unconverted Pharisees and religious leaders of Israel desired to see a literal kingdom of Israel with the Roman yoke removed. That was their concept of Messiah/King. But they would be taught that the literal, visible Kingdom of God would only be established after the second coming of Christ.
But Jesus held his peace. And the high priest answered and said unto him, I adjure thee by the living God, that thou tell us whether thou be the Christ, the Son of God. Jesus saith unto him, Thou hast said: nevertheless I say unto you, Hereafter shall ye see the Son of man sitting on the right hand of power, and coming in the clouds of heaven. (Mt 26:63,64).
And this ties in with Daniel 7:13,14:
I saw in the night visions, and, behold, one like the Son of man came with the clouds of heaven, and came to the Ancient of days, and they brought him near before him. And there was given him dominion, and glory, and a kingdom, that all people, nations, and languages, should serve him: his dominion is an everlasting dominion, which shall not pass away, and his kingdom that which shall not be destroyed.