The pastor/priest/whatever, wasn't in a situation where he felt it was morally wrong for him to marry a specific couple because of their sexual orientation. He/his church chose not to marry them because of a specific belief they posted about on Facebook.
If the story is accurate, it was an idiotic decision by the church. But let the public punish the church by refusing to go there anymore. The govt has no place interfering in this issue.
Yep, different issue. Many Christians have all manner of unScriptural views - which doesn't mean they aren't Christians. So, the pastor has probably alienated them so that they'll never go anywhere near his church. Where if he had married them (if appropriate/they are both believers), he would have had the opportunity to enlighten them or influence them, on that and other important issues. I don't find those in the NT evangelizing unbelievers present and opinions checklist requirement for salvation. And neither is their for marriage, excepting they are both believers.