...and they don't even have to explain it to your satisfaction. It may be that they don't know what they're talking about, but it doesn't matter. If they're mental midgets who can't find proof for their beliefs, you can ignore them.

But likewise (and that's the key term in all this...LIKEWISE) they can ignore you or anyone else who says something they disagree with...or they can choose engage with you.

That's the beauty of freedom of expression and being able to criticise something. You don't have to convince the masses, you don't have to be eloquent or even politically correct. You can just say what you think or feel.

Why do you seem to take it personally when someone says something against Islam? Just write them off as an ignorant non-believer and move on, or else try to engage them in some intellectual discussion to change their mind. But don't try to stifle the freedom they and you both should have to express yourselves.
That's what most of us on here are so passionate about -- the ABILITY to even have this discussion! That's what we want to ensure.