NT in 40 Days: Luke 15-19

Once, having been asked by the Pharisees when the kingdom of God would come, Jesus 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

If the kingdom of God is within (or among) us, what does that actually mean?

It's the church, and not the building sort, but as the Greek word ἐκκλησία (ecclesia) implies, it's an assembly.

To me the church is more than a mere assembly; it's a community. If you ask me what the difference is between my church and some other one, I doubt I could answer it. Just the same, I invite people to mine because it's the community I know.