A professor I had years ago had an interesting idea. His thought, and of course we're speculating here, was that there was a pattern to the movement of the gospel and the establishment of Christianity. Mark 13:10 says that "the gospel must first be preached to all the nations" before Christ returns. It's one of the reasons why bible believing and educated Christians knew that Harold Camping had made an incorrect prediction. The gospel, the good news, has to reach all nations (Matthew 28) before the age of the Church is complete, before the mission of the Church is accomplished. The professor I mentioned earlier thought that we were getting close, not only because of other signs, but because we are getting close to having reached all languages and people groups. He thought one could trace a clear path of the spread of Christianity across the globe. Now, granted there are offshoots and establishments here and there but I think I agree with his historical perspective.
Christianity began in Jerusalem, obviously, and spread throughout the Roman Empire, heading West. Paul's hope was to end up in Spain according to some of his last writings. After Europe Christianity continued west across the Atlantic to the Americas. While the diagram above doesn't show it, most recently Christianity is blowing up in Asia, especially China. My professor speculated that perhaps as Christianity moved through Asia and back to Israel again, the gospel has made its circuit around the globe. Watching the recent revolutions in the Arab world can't help but make me think that those states will soon be more in contact with Christians, missionaries and the Gospel than ever before. As the new generations in the Arab world come up wanting freedoms and democracies, a break from traditional Islamic states, so also comes more influence from the outside world and, I hope, more openness to Christianity. We live in exciting times.