I have no objection to you deleting any comment you wish from your own post. It’s your post! That’s not about freedom of speech. Commenters can say anything they like on their own forum — not yours.
On the other hand, assuming that everyone should already agree with you is a bit “out there” to say the least. Some good-faith scrubbing of your assumptions, I think, is well-warranted. Indeed, in my experience, the more a belief “cannot be questioned,” the more likely it is to be bogus.
When you say things on the Internet, though, some folks will disagree, some vociferously, some rudely. If that’s a real problem, do what you did — delete the post if you can — or ignore it, or ridicule it, or debate it. If those options aren’t good enough, then it’s important to realize Internet is not really “for” sensitive souls. Assholes have as much right to speak to you as you have to speak to them. If that’s not good enough, I suggest the “Log Out” button, or even just call your service provider, cancel service, and spend all that good money on something more soothing. “Soothing” will definitely not be found on Facebook.