The first case is that of a captive or a prisoner of war. Obviously he has no choice, but he must preserve his faith and return home as soon as possible.
The second case is that of an unbeliever in the land of the unbelievers who sees the light and embraces the true faith—in other words, becomes a Muslim. He must leave as soon as possible and go to a Muslim country.
The third case is that of a visitor. For long, the only purpose that was considered legitimate was to ransom captives. This was later expanded into diplomatic and commercial missions.
With the advance of the European counterattack, there was a new issue in this ongoing debate. What is the position of a Muslim if his country is conquered by infidels? May he stay or must he leave?
We have some interesting discussions of these questions, after the Norman conquest of Muslim Sicily in the eleventh century, and more especially from the late fifteenth century, when the reconquest of Spain was completed and Moroccan jurists were discussing this question. They asked if Muslims might stay. The general answer was no, they may not. The question was asked: May they stay if the Christian government that takes over is tolerant? (This proved to be a purely hypothetical question, of course.) The answer was still no; even then they may not stay, because the temptation to apostasy would be even greater. They must leave and hope that in God’s good time they will be able to reconquer their homelands and restore the true faith.
This was the line taken by most jurists. There were some, at first a minority , later a more important group, who said that it is permissible for Muslims to stay provided certain conditions are met, mainly that they are allowed to practice their faith. This raises another question: what is meant by practicing their faith? Here we must remember that we are dealing not only with a different religion but also with a different concept of what religion is about, especially in regard to the Shari‘a, the holy law of Islam, covering a wide range of matters regarded as secular in the Christian world even during the medieval period, and certainly in what some call the post-Christian era of the Western world.
All of these discussions relate to the problems of a Muslim who, for one reason or another, finds himself under infidel rule. The one possibility that, it seems, never entered the minds of the classical jurists was that a Muslim might, of his own free will, leave the House of Islam and go to live, permanently, in an infidel land, the House of War, under infidel rule. But this is what has been happening, on an ever increasing scale, in recent and current times.
There are obviously now many attractions which draw Muslims to Europe, particularly in view of the growing economic impoverishment of much of the Muslim world and the worsening rapacity and tyranny of many of its rulers. Europe offers opportunities for employment and benefits even for unemployment. Muslim immigrants also enjoy freedom of expression and levels of education which they lack at home. Even terrorists have far greater freedom of preparation and operation in Europe—and to a degree also in America—than they do in most Islamic lands.
There are some other factors of importance in the situation at this moment. One is the new radicalism in the Islamic world, which comes in several kinds: Sunni, especially Wahhabi, and Iranian Shi‘ite, dating from the Iranian revolution. Both of these are becoming enormously important factors. We have the strange paradox that the danger of Islamic radicalism or of radical terrorism is far greater in Europe and America than it is in most of the Middle East and North Africa, where rulers are more skilled and less inhibited in controlling their extremists than are Westerners. Nevertheless, growing numbers of Muslims are beginning to see Islamic radicalism as a greater danger to Islam than to the West.