Would a Jew have to bake a cake for a Nazi wedding? Forcing a Christian to bake a cake for a homosexual wedding is the functional equivalent of forcing a Jew to bake a cake with a swastika on it.
But in keeping with the law, the Jewish baker would have to bake a cake, minus the Nazi trappings, for anyone who asked for it. Bottom line is, force nobody, under the laws of contract, to do anything that would make him a participant in behavior of which he doesn't approve and would amount to an infringement of his own beliefs. It's a free speech issue, but not in the way the Left imagines it.