Convert them or kill them

I think one of the most terrifying phrases is “convert them or kill them”. It scares me to think that someone could be completely fine with the idea of killing someone because they will not join your club. I always try to be empathetic and attempt to understand where someone may be coming from, but when trying to unpack and understand “convert them or kill them” all I can think of is being very sick in the head. On a grander scale I also imagine a police state “Fahrenheit 451” or “1984” type government where everyone has to think the same.
For me, it doesn’t matter where that phrase is coming from to make it seem sick. If an Islamic leader says it, many Americans will be quick to say how awful that is. I’m pretty sure people would freak out if an atheist were to say that, and that would be myself included. But for some reason it’s okay for Christians to say this. Phil Robertson of “Duck Dynasty” said the phrase on Sean Hannity’s show the other day and I’ve also heard Ann Coulter say it. I’m sure if I really cared I could find many examples of Christians saying that sort of thing, but it doesn’t really matter how many times it’s been said and who exactly said it. It just strikes me that it’s fine to say Islam is not a religion of peace and Christianity is commonly seen as a religion of peace. I’ve even come across atheists that have told me that Christianity isn’t so bad and it’s more civilized.
How peaceful is “convert them or kill them”? It’s not that it’s just crazy Christian people saying that sort of thing, their bible says it. There are many stories throughout the bible of cruelty and violence towards outside groups. Phil Robertson used bible verses to support why we should “convert them or kill them”. How does that attitude not immediately make one think of the Nazis? How can people point to the Holocaust and say how awful that was but not cringe when someone says something along the lines of “Muslims should become Christians or die”. Does the concept of “killing people because of their beliefs/culture” not ring a bell?
People need to wake up and see that neither religion is a religion of peace.