Mark Murphy has closed the comments period on his letter to the APA (which follows a petition and a counterpetition), and he is collecting signatures by email. The final version of his text, together with a link to email him a signature, is here.
I would like to quote from the final paragraph of his letter:
The APA is a diverse association marked by deep pluralism. Its members can rightly expect that the APA will respect the deep differences among them in judgments about how it is reasonable for individuals to live and for communities to organize themselves, and it is far from clear that the suggested change in course does respect those differences. It has been correctly claimed by some who argue for the change in policy that any such respect has its limits: the APA of course would not respect colleges the common life of which was built on racist norms. In our view the appeal to this argument highlights what is involved in excluding or marking as beyond the pale the job advertisements from these Christian colleges. There is no serious reasoned disagreement on racist norms; the APA can rightly feel free to speak on behalf of its members to condemn any such. What would be involved in changing the APA's policy with respect to these Christian colleges is that the APA would be taking an official stand, speaking on behalf of all of its members, on what are still matters of deep and reasoned controversy among them: whether so-called traditional marriage has any privileged normative status and whether sexual activity outside such marriage is morally suspect. For the APA to take such a stand would be a grave error and an injustice.