Because during the tribulation the people left on the earth will be involved in a one world religion, do you believe the news story about the Pope while in Turkey praying towards Mecca with the Muslims gives validly to their religion and is an indication how easy it will be to convince people to follow a one world religion? Is there any were else in the Bible that speaks of a one world religion besides Revelation 17?
After his comments about Islam being a violent religion, the Pope has been trying to make amends without retracting his statement. Visiting a mosque and praying toward Mecca are attempts to do this. Lately the Catholics and the Moslems have found that they share a common affection for Mary, although the Catholic Church takes it to a greater extreme. I believe that after the Rapture, the remaining Catholics will have no trouble joining ranks with Islam and forming the core of the one world religion.
While the Bible contains numerous references to the worship of idols and false gods, and the Roman Empire attempted to enforce Emperor worship on all their conquered nations, the one world religion is a concept uniquely suited to the end times scenario.