Christians; If you think the Qu'ran is from Satan...?

Because they're uneducated. They say that Allah is a false God, which is the same as calling their own God false. They're clueless about the fact that Christianity, Islam, and Judaism all follow the exact same God. They're also clueless that Isa and Maryam are revered as holy in the Qur'an. And they're probably clueless that Isa and Maryam are Jesus and Mary. They're brainwashed.