The thing that always gets me about these is the underlying panic in their tone. A murky they (equally likely to be a left-wing they or a right-wing they, depending on who forwards the particular item) are always threatening to destroy/despoil/illegalize some cornerstone of life that us normal, good-willed, live-and-let-live folks grew up with and have had as our traditions for centuries.
Scientists are going to criminalize Christianity.
Christians are going to criminalize science.
Left-wingers want to turn us all into gay government-dependent drug using secular humanists who have casual abortions. (Why would we need abortions if we were gay, exactly?)
Right-wingers want to turn us all into McCarthy-era radical Christians, relegating women to domestic servants as they despoil the environment and wage war for the fun of it.
The foreigners are taking over.
The sky is falling, we need to run and tell the king.
I have indulged in my own rants from time to time; I understand that if there's something that's bugging you it can feel good to engage in the literary equivalent of Primal Scream Therapy. But the thing about a rant is, that's all it is. A lot of heat, very little light, as they say.
I have pretty much all of The Usual Suspects in my family trained not to forward me urban legends any more, because I always send them (and everybody else on the list, if it's not bcc:ed) a terse message of "You've been fooled by a hoax. Here are the facts: (and a link to the applicable Snopes page)." After being embarrassed this way a few times, they don't stop sending out urban legends ... they just stop including me on them. I spoil the Willing Belief of Untruth party, I suppose.
But you can't debunk a rant, because it's not about facts, it's about feelings. When somebody shrieks "Soon the P.C. crowd won't let you discipline your children!!!!!1!" there's no statement of fact you can point to ... and trying to refute it just turns you into a member of the nebulous they and Part Of the Problem.
So when I get a rant, I just sigh and delete it. What else can you do?