Churches can be compelled to do a lot of things. Mormons no longer sanction polygamy. In Canada they are prosecuting clergy for "hate" speach.
HostileTerritory
Can churches be forced to marry two people of different religions if the church doesn't recognize their marriage?
A court in British Columbia ruled that any public official who has the authority to marry people must marry any gay couple who ask to be married or else be removed from office. Just last week there was a thread about an Episocpalian bishop in Canada who wants to extend the duty to perform "gay marriage" to all clergy.
I can imagine that any newspaper that publishes wedding announcements will be required to also publish "gay wedding" announcemtnts. Canada after all does not have a right to free speech in its constiutution. If the leftitst have their way, the 1st amendment would be gutted for any criticism of their favorite mascots.