“If anyone forces you to go one mile, go with them two miles.” ~Matthew 5:41
The author is confused on more than one count. Exegetically, we should start with the fact that Jesus says that he has not come to abolish the law but to fulfill it. Whatever Jesus says, it is in accordance with the Old Testament law ("anyone who sets aside one of the least of these commandments and teaches others to do likewise will be called least in the kingdom of heaven.") Marcion was a heretic. Second, Jesus ups the ante on sexual morality including divorce. His sexual ethics are stricter than anything on offer; it is less permissive not more. For example, one can commit adultery in one's heart even before committing the external act. Third, on the traditional, orthodox view in Christianity, adultery, incest, homosex (yes, it's a word), bestiality, etc. are intrinsically wrong. This entails that there are no circumstances in which they are morally permissible. Some think that participating in a gay wedding is participating in something that condones homosex which is intrinsically wrong. Whereas, it is not intrinsically wrong to slap someone, to give one your cloak, to go an extra mile when forced to go one, or to give to someone who asks. Finally, her view seems to entail the following absurdities when her argument is taken to its logical conclusion: If someone asks for aid in having an affair with one person, you should aid and abet in two affairs; if someone asks you to bake a cake for a Westboro Baptist demonstration, you should bake two.
Her argument is supposedly based on a Christian ethic of love; but love takes on many forms and some ways of loving are appropriate and others inappropriate.
If we “snatch one person from the fire” by refusing to condone behavior we believe is immoral, but send hundreds and thousands of others fleeing churches and Christianity entirely, what have we really accomplished? Someone else will make that cake and fewer and fewer people will look to Christianity for love and hope. We will have won a battle that we were never called to fight in the first place, but lost the war.The tacit empirical claim here, that by not participating in some actions which appear to condone certain sexual practices many will flee Christianity, is dubious. Christianity flourished from the very beginning in a culture and against a background that was sexually promiscuous and in many ways like our own. In fact, one of the things that stood out about Christians was their strict, sexual ethics (such that the slur against Christianity was that it was "a religion for women.")