The Satanic Court of the United States ruled that God's own definition of marriage is wrong. That has a very biblical ring to it-- something like the Obamanation of Desolation.
For the present, churches or ministers cannot be forced to marry same-sex couples, or else to abandon their mission. But we have to presume there will be a future. 4 decades ago, many of us recall the continual battle to ratify the "equal rights amendment" to the constitution. One objection to it was that it would result in same-sex marriage. But left-leaning columnists, such as economist Sylvia Porter, for one, downplayed that because "the definition of marriage is one man and one woman." While I don't know about Porter, many of these advocates obviously changed their positions. Legal same-sex marriage just wasn't really taken seriously. Do times change?
So now, the question of whether religious bodies must define marriage to include same-sex couples if they want to legally exist has to look to the future. No, it's not reasonable right now that they can be forced by law to redefine marriage, but 30, 40, or 50 years from now this may be different-- as we have seen today, looking back 30, 40, or 50 years. But the next step likely won't be forcing them by government hand to change-- it will be tax status. In order to retain exemption from property taxes and still be a 501.c.3 institution, a church will have to have a statement of "marriage equality."
You think this won't happen? What did you think about legal same-sex marriage 40 years ago?