He asks, is the principle "the end justifies the means" contrary to Islam? Yes.

In Islam, we do not have the concept that the end justifies the means. Just as the goals must be legitimate, the means must also be.

Legitimate. We do not have anything called "the end justifies the means."

Some say that certain Islamic figures, like Salahuddin, were ministers in the Fatimid state and then turned against them for this purpose. Who says that Salahuddin was a minister in the Fatimid state?

This is false talk, it's not true. Salahuddin was with the Zengid state.

His uncle was Nur ad-Din Zengi, and this has nothing to do with the Fatimid state.

He is the one who wiped the Fatimid state off the face of the earth in Egypt.

How can it be said that he was a minister in the Fatimid state? This is not correct.

And Allah knows best, and may Allah's peace and blessings be upon our Prophet Muhammad.