The article in the link in the OP was written by gays. No Christian must ever participate in a gay wedding. It isn't enough to advertise that you specialize in normal weddings but then serve gays when they demand it "to protect yourself legally" (read the whole article). The punishment from Jude 1 doesn't have gray areas. You either refuse to enable a cultural homosexual takeover (using the core of all culture-marriage) or you spend eternity in the Pit of Fire.
I disagree. True Christians adhere to the teachings of Christ. Wedding vendors do not participate in wedding ceremonies. Baking, photographing, catering are not sacramental rites or rituals. They are the services such vendors are in business for.
Perhaps, if a vendor fears for the status of their immortal soul by baking wedding cakes, they should morally vet each and every customer to assure no sinners ask for their services. Should 'Christian' vendors provide a wedding cake for a adulterer? What if a customer failed to remember the sabbath and keep it holy? Maybe there is a customer who regularly takes the Lord's name in vain. These are sins enumerated in the Ten Commandments, unlike homosexuality.
Face it. Wedding vendors who refuse to provide the exact same service to homosexual couples as they provide for heterosexual couples are afraid of marriage equality. Why? Ignorance, suspicion, reliance on wicked stereotypes, open bigotry. Is that the way Christ commanded us to treat one another?