How can the wars of conquest by later Muslim rulers be justified?

Not every war fought by a Muslim state is a religious war, and Islam is not answerable for every act of Muslim rulers. Each of these wars has to be judged on its own, by the standards of its time, and the Holy Qur’an defends no unjust war.

In the time of the Holy Prophet Muhammad (saw) no war of aggression was fought. So it is a fair question how the later conquests should be seen. But the question quietly assumes that every war fought by Muslims must be a religious war. That is not so.

A religious war in the sense of the Holy Qur’an is bound by strict conditions, as the first verse above shows. Most wars in history were not religious wars. They arose from political situations, from pressures and from disputes between states. Sometimes both sides were at fault, sometimes one, and sometimes both acted in good faith and were simply mistaken.

When empires later arose, they were Muslim states. They were not Islam itself. Their wars must therefore be judged by the customs and the relations between states of their own age, not by the ideas of today.

If such a war was not justified even by those standards, then it was wrong, and no one needs to defend it. The Holy Qur’an certainly does not. It forbids going beyond the limit and demands justice even towards the enemy.

So it helps little to lump all wars together. Whoever thinks a particular war was unjust should name it precisely. Then one can examine whether it had a religious or a political cause, and whether there was any justification for it at all.