But the local church can be organized, and that is where the difficulties begin. Jesus prayed that the universal church might be as unified as is the Godhead (John 17:11, 21). Though the early NT church experienced remarkable unity (Acts 2:43-47; 4:32-35), cracks in the walls began to appear. Ananias and Sapphira were dishonest and were put to death by the Lord (Acts 5:1-11). Paul warned of power-hungry elders (Acts 20:29-30). John called out the rebellious Diotrephes (3 John 1:9-10).

Since then the local churches have divided into a plethora of factions and denominations.

I do not see any way that Jesus' prayer for unity will be answered in this present lifetime. But I also cannot believe that Jesus could pray a prayer that could not possibly be answered. So when will His High-Priestly prayer for church-wide unity be answered?

I believe it will be answered when Christ returns to gather His own to Himself (John 14:1-3; 1 Thess. 4:13-18). All Christians will be purified at the Judgment Seat of Christ (Rom. 14:10; 1 Cor. 3:12-15; 2 Cor. 5:10). The Bride of Christ will then be purified (Rev. 19:7-8). Then it is that the Church Universal will be truly unified.

I can hardly wait until the time when there will be no division of the Body of Christ between Roman Catholicism, Greek Orthodoxy, Russian Orthodoxy, and Protestantism. We will all be what Christ is aiming for in His building -- one Body, the Body of Christ (Rom. 12:5; 1 Cor. 12:13).