Speaking as someone of an agnostic bent, I find the experience of someone telling me that I’m going to hell more annoying and frustrating than anything else. I also tend to view it as a warning sign. If someone is, as you point out, so convinced that their faith is correct that they will willingly make statements which they know will alienate friends and family, then I have to wonder what else they will do in the name of faith. Will they murder? Will they marginalize? Will they exclude? I know, I know, it’s a slippy slope argument. But it does have historical precedent, unfortunately.