The fact that islam rules 1/5 of the planet proves to me that there is no supreme being and that humans are fundamentally primitive, hopeless beings. Until islam withers, I'll feel the same way. Communism in the USSR in my younger days made me feel the same. We'll see if both evils can be reduced.
I suspect that you have the same problem that many radical muslims have. They tend to think of Christians as single entity. Muslims are no more monolithic than Christians and Jews are.
David Kilcullen ( A counter insurgency specialist) notes that if we insist on seeing an Islamist from Java as the same thing as a Jihadist from Yemen then we are doing the interest aggregation and interest articulation of the Jihadists for them.
The distinction between evil and not evil is the ability to disaggregate them.
Satan is prince of this world, this age, and we are here to decide who we will follow. We have been given "free will" for this test and along with that, a set of instructions on how to defeat Satan, leader of Islam. Don't think because evil is here that there is no God. You will stand before Him one day. Until then, look for truth in all things and you won't find that in many of our Christian churches today.
There will always be evil. Without evil we would never have evolved from single cell organisms. But we must always fight it.