Why do Christians still pray for the coming of the Kingdom?

Although Christians already experience the glory of the Kingdom, the end of the age and the regeneration of all things is yet to come. Only then will the Son “deliver the kingdom to God the Father, after destroying every rule and every authority and power,” so that “God may be all in all” (1Co 15:24, 28; see Q368). In this blessed hope, like the earliest Christians, we call upon God as our Father and upon the Name of the Lord as our Savior and King, exclaiming “Abba, Father!” and “Maranatha: Come, Lord!” (Mrk 14:36; Gal 4:6; 1Co 16:22; see Q401, Q243).