If you're sent to hell and punished for being evil how does that make the devil such a bad guy? If you did bad stuff in life you're supposed to be one of his boys.
Never was it mentioned in the bible nor in earlier Christian teachings that the Devil is the ruler of hell and is the one punishing the sinners. The Devil was named "Ruler of the World" for a reason. He was meant to suffer in hell alongside the sinners.
In Scotland there is tension between Catholics and Protestants that often manifests itself in fights between supporters of the two major football teams of Glasgow, Rangers for Protestants, Celtic for Catholics, going as far as bombs being sent to a managers house in the post..
This is quite a generalization. The old firm is beyond just catholic vs protestant. That is simply the tip of the iceberg and placing the accountability of the old firm's violence to religion is a wee bit unfair. It goes all out with politics, social ideologies, celtic-anglo tension, native-immigrant tension, and even the policies in the neighbouring Ireland.
Christianity is the Only Religion where someone as Evil as Hitler could be Saved but a person who has Never Killed One Person let alone Six Million can be sent to Hell based on what they Believe about God. This is very problematic IMO...
Islam allows lots of massacring war-waging Jihadists including their prophet to heaven while damning innocent infidels to hell. I don't know how that is different.