It may even be . . . that the Kingdom of God means Christ himself, whom we daily desire to come, and whose coming we wish to be manifested quickly to us. For as he is our resurrection, since in him we rise, so he can also be understood as the Kingdom of God, for in him we shall reign. 86

Catechism number 2819

"The kingdom of God (is) righteousness and peace and joy in the Holy Spirit."90 The end-time in which we live is the age of the outpouring of the Spirit. Ever since Pentecost, a decisive battle has been joined between "the flesh" and the Spirit.91

Official source ↗