Why do Atheists take offense when a Christian tells them...?

As an agnostic I am told that sometimes as well. I really don't take offense to it and I doubt many atheists do either, they probably think its very funny when people tell them that. Logically, there is no point to hell. Perhaps heaven or an afterlife of some sort exists, but why would god want to send all these people to hell when he could simply end their existence? Eternal suffering wouldn't really accomplish anything, maybe it exists but probably only for your Hitler type people.