The organization that Murray-O'Hair founded has been re-named American Atheist.
I called there and talked to their PR guy Nick, to find out if in fact the John Lauritsen she was responding to was (is, he's still with us and in his 70s) was indeed the early gay rights activist whose bio I linked to.
He couldn't confirm that, but he was aware of the letter and said it was "regrettable," and he had heard, in fact, that in correspondences between two, whether that Lauritsen is the gay activist or not, Murray-O'Hair perceived him to be something of a chauvinist.
So I looked up Pagan Press, and found a phone number to a Calamus book store in Boston, that carries the gay rights activist's books.
The guy at the book store also couldn't verify that that Lauritsen is the one whom Murray O'Hair was addressing, but said "yeah, in all probability is."
"Who would know?"
"John would."
So he suggested I send him the inquiry at the e-mail contact at Pagan Press.
So I sent this:
Hi, John;
I have an academic question for you - are you the John Lauritsen that Madeline Murray O'Hair responded to on May 20, 1976 with profanity laced homophobic tirade in response to a correspondence you sent to the California Chapter of her seperationist organization that had been been forwarded to her, that is linked to beneath here?
http://www.discord.org/~lippard/Lauritsen-OHair.pdf
If so, could you be so good as to provide me the text of your correspondence that she would have been responding to?
Thank your for your attention and assistance.
Jeff
So we'll see what, if anything, comes back.