Even with this “roundabout solution” you have proposed, there would be “Christian churches” which would allow homosexual weddings and let the homosexuals join the “Christian cake club”. It would be just one more opportunity for those promoting the gay agenda to get some press, showing how they are so persecuted by the rest of us.
No, the baker runs the club.
And the baker only allows churches in that conform to his or her Christian beliefs.
If those beliefs deny marriage to homosexuals, then no affiliated church will be a church that will marry homosexuals. Therefore, no homosexual will be a member in good standing of that church, and therefore they will not be allowed to be a member of the club.
You see, the baker isn't denying wedding cakes to homosexuals. He's providing wedding cakes to members of the club - and the members of the club have to also be member in good standing of an affiliated church.
So how is a member in good standing in a church that doesn't marry homosexuals going to want a wedding cake for a homosexual wedding? The very request would violate the beliefs of the associated church, and thereby identify them as not in good standing with that church - and that would be verified by the pastor or priest.
Look, the idea is not to stop homosexuals from buying wedding cakes. The idea is to prevent homosexuals from being able to force people to make them wedding cakes against their religious beliefs. The difference is gigantic.