Then don’t rent it out. Let church “members” use it after making a tax deductable donation. That way the state loses twice.
You've got a good point there, but I don't think the church should be forced to take their property "out of the market," thus drastically reducing their opportunities to lease the property as they choose.
I would dispute that this was really a case of discrimination based on something like sex or color or race, a personal attribute, rather than a matter of act or behavior.
If a person who "happened to be gay" wanted to rent the facility to house a sports tournament, a cooking class, or a high school reunion, I don't think the property owners could object. But if the activity to be held thereon is something the owners are morally prohibited from cooperating with, they are not discriminating against the person, but drawing the line an an objectionable activity--- in this case, a marriage which Christianity, Judaism, and Islam would find, on the basis of their Scriptures, "abominable."
It's like a professional event videographer being asked to produce a favorable video of a Holocaust-denial-Hamas-support rally. If the photographer is (say) Jewish, he can't discriminate against a Muslim customer per se, but surely he can decline to take a job which requires him to accommodate an activity he finds morally offensive?