One of the worst places on the Internet is Facebook. It is full of very weird people, vicious people, and nut jobs.
You might join a site discussing Whatever, or communicating with a friend, and then, out of nowhere comes some horrible creature who, safe behind his computer, feels he can say what he wants, how he wants it.
There is no sense in responding. No sense in reading a single word he posts.
This is not a debate or discussion, this is a someone looking for attention.
Do not respond.
Block. Just Block. Block and post what you want. Read what you want.