Ranting against a poorly understood concept

What verbs (or phrases) describe the behavior of expressing negative opinions on a topic the speaker is seriously misinformed about? What can be such a person called? "Droning"; "incompetent", "demagogue" or "ignorant" aren't quite the terms I'm looking for. Perhaps a combination of "judgmental" and "ignorant"?

Example:

He was going on and on about how gays are depraved immoral animals who wanted to destroy the traditional marriage, but could not name a single marriage broken by, or crime committed in the name of homosexuality.

Solution 1:

You example immediatley brings to mind bigot, although that is not necessarily based on ignorance or misinformation:

a person who is obstinately or intolerantly devoted to his or her own opinions and prejudices; especially : one who regards or treats the members of a group (such as a racial or ethnic group) with hatred and intolerance

One could argue, though, that such tenacity to one's preconceived ideas can only be the result of willful ignorance and the refusal to accept facts that contradict those preset opinions or refusing to become better informed.