Q. What exactly did Jesus mean when he replied “The kingdom of God does not come with your careful observation, nor will people say, ‘Here it is,’ or ‘There it is,’ because the kingdom of God is within you?” (Luke 17:20-21
A. First, it’s important to recognize that Jesus was talking about phase one of the Kingdom, which is the Church. When Jesus returns to set up phase 2, His Millennial Kingdom, everyone on Earth will know it has arrived (Matt. 24:30).
That said, most competent study Bibles make note of the fact that the Greek word translated “within” can also be translated “among”. When you realize who Jesus was talking to (Pharisees) you know He couldn’t have meant the kingdom was within them because they weren’t believers. Therefore, He must have been pointing out that the kingdom was among them.
This interpretation makes more sense since there were already untold numbers of believers in Jesus in their proximity who couldn’t be distinguished from those who weren’t believers. (This is still true today.) Also, as it concerned the Pharisees, the personification of the kingdom was standing there among them and even with their careful observation they didn’t recognize Him because He didn’t look like they thought He should.