It is odd that religious people are still waiting for the establishment of the Kingdom of God in view of Mark 9:1, which reads: “Assuredly, I say to you that there are some standing here who will not taste death till they see the kingdom of God present with power.”
It doesn’t take a theologian with lots of letters behind his or her name to discern that this verse presents one of only three possibilities.
 Jesus didn’t know what He was talking about and, with the Jew’s rejection, He failed in His mission to humanity. This is a bit embarrassing for an all-powerful Son of God to fail His mission because of human intervention. Or…
 There are some really old people living today (some 2000+ years old!) still running amuck on earth and awaiting this yet-to-be-established Kingdom. This absurdity really ought to be enough to come off the position that Jesus’ Kingdom is yet to be established. Or…
 Jesus did what He said He would do and all this talk of His setting up some physical throne on this physical earth is the fantasy of overactive, misguided imaginations. That, in fact, this is the most consistent position of the three ought to be just as obviously right as the others are wrong.
Therefore, we should believe just exactly what Jesus said! He established the Kingdom He promised, giving Peter the keys to that Kingdom, whose doors Peter opened on the day of Pentecost (Matthew 16:18; Acts 2:47). He reigns over a Kingdom that is, indeed, in existence and thriving this very day (1 Corinthians 15:25); “he must reign” is present tense, He is reigning now. Finally, those who are Christians are citizens in this very Kingdom, because “He has delivered us from the power of darkness and conveyed us into the kingdom of the Son of His love” (Colossians 1:13); “conveyed” is past tense therefore some in Paul’s audience had already entered the then-existing Kingdom.
Was Jesus weak and mistaken? Is the earth populated with two-thousand-year-old people? Or is Jesus King of your life right now, and you a part of His Kingdom, which exists now? What are you waiting for?