When Jesus taught his disciples how to pray in Matthew 6, what did He mean by the words, “Thy kingdom come?” Obviously, he meant for them to pray for the arrival of His kingdom. The Old Testament had prophesied that coming in numerous places, including Daniel 2:44, “And in the days of these kings the God of heaven will set up a kingdom which shall never be destroyed; and the kingdom shall not be left to other people; it shall break in pieces and consume all these kingdoms, and it shall stand forever.”
This prophecy was fulfilled in the first century. Remember, Jesus promised the establishment of His kingdom during the lifespan of his contemporaries (cf. Mark 9:1). Those prophecies were fulfilled at His resurrection—this attested to by Peter who wrote in Acts 2:36, “Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.” Jesus is the King of kings and Lord of lords. His kingdom is present with power. In fact, Paul wrote that those who became Christians were conveyed into the then existent Kingdom in Colossians 1:13.
Religious people today who continue to pray “Thy kingdom come” are either ignorant of, or refuse to grant that it already HAS! So, while a beautiful sentiment, the request should not be prayed today. Instead, we should praise God for having fulfilled His promise. Glory to God that He has exalted His Son. Today, Jesus is King in His kingdom!