Christian groups should stop being general and start being denominational. At that point colleges will have to deny equal access to real religions even though they receive public funds and they will be discriminating against real religions purely on the basis of their religion.
Colleges need to de-fund frivolous groups. In the name of controlling college costs and reducing college debt, they should cut off all support for clubs and groups on campus. It makes economic sense, and it will eliminate the discrimination against Christians - a double win.