What the Bible says about Maranatha
(From Forerunner Commentary)
When a converted person prays, “Your kingdom come,” he confesses his hope to God, voicing his desire for God's direct rule, which he shares with the undisputed Lord over all things. In this way, he comes into a unity of purpose with Him and asks God to continue accomplishing His purpose, not only in him but also in others whom He will call and prepare for the same goal (see I Timothy 2:3-4; Romans 10:1). As the author of Hebrews suggests, this expression of solidarity with God's purpose is founded on the sure reality of His faithfulness (see I Corinthians 1:7-9).
This petition also requests that God move world events toward the return of Christ to establish His Kingdom on earth. In this way, the petitioner expresses his desire for the dissolution of this current, evil, anti-God system and the arrival of goodness and peace for all. This is the sense of the first-century Christian cry, “Maranatha!” an Aramaic term that means “O Lord, come!” (I Corinthians 16:22; see Revelation 22:20). It calls out for the end of humanity's sins and miseries and the beginning of a new world where God dwells with men and all the faithful have entered the joy of the Lord (see Revelation 21:3-5; Matthew 25:21, 23).
Richard T. Ritenbaugh
The Model Prayer (Part Four): Your Kingdom Come