This case does not pit gay rights against Christian faith. It pits certain Christians against anti discrimination laws.
The issue here is that the cake-baker refused to sell a wedding cake to a gay couple. He offered to sell them other baked products, like cookies, but refused to sell a cake. They did not request a different cake from any other cake that he would sell to a heterosexual couple. It wasn't anything about the cake, it was that a gay couple wanted to buy it.
This is in contrast to another Colorado (IIRC) baker who refused to put a pro-fascist message on a cake. Instead, she made the cake and provided the customer with a frosting-bag so the customer could write whatever (offensive) message they wanted. This was upheld on First Amendment grounds: the baker couldn't be compelled to "speak" in frosting on a cake.
The cake case before the Supreme Court now is whether a business owner can refuse to sell a generic product based on a characteristic of a customer which puts the customer in a class receiving heightened scrutiny. I don't see how this is different from a business owner's refusing to serve BBQ to an African American. (That case was decided against the business owner; and saying my religion says black people are marked by God, so it violates my religion to serve them shouldn't make the business-owner win the case. Nor should it help to say, "I'm an artist in pulled pork" and that makes what I sell different from other products).
In any event, Christians should be careful what they wish for. They may find the cool, arty stores will refuse to serve them if they win this case.
The baker is going to lose his case big time . The baker refused to sell his cakes simply based on the sexual orientation of the couple .They were not asking for any special artistic design, just a cake the baker was selling to everyone else .It may well be a 9to 0 decision.