Before I start, for the avoidance of doubt, let's get three things clear:
1. I'm not a Christian, and I find some elements of Christianity to be not only irrational but also immoral.
2. I'm not gay.
3. I fully support two people of the same sex being able to get married, just like two of the opposite sex, and I find fear or hatred of people because they are homosexual/lesbian/bisexual to be both irrational and immoral.
So from a libertarian perspective, the Asher's Bakery case in Northern Ireland is an interesting one.
The long and the short of it is that a gay rights activist in Northern Ireland asked a bakery to bake a cake with a pro-gay marriage slogan on it, and the bakery objected because the owners oppose gay marriage, because of their religious beliefs.
The court has ruled that refusing to bake the cake is illegal "discrimination". What this ruling represents is a fundamental infringement on two rights:
1. Freedom of trade;
2. Freedom of speech.