People are being sued for refusing to participate in gay marriages. A bakery was pretty much driven out of business because they refused to make a cake for a gay marriage. The gay couple who were getting married shopped around until they found a baker who refused then sued them. That is a pretty militaristic attack one someone's religious beliefs and it deserves heavy push back. As a photographer I think it would be a blast to shoot a gay marriage (if I shot a marriages at all) but as an artist I am violently opposed to anyone telling me how I should use my art and who I have to accept as a client.
For all the poo pooing the left does about the war on religion there is steady and concentrated efforts by a large group of people to drive religion (and by religion I mean Christianity) out of open society. Basically the reason religious liberty is an issue is because it is under assault. The reason it is not an issue in Europe and some other places is because it has already lost. I am an atheist but I am also a libertarian so I oppose forcing beliefs on other people and support of gay marriage is at its heart a belief.