I think you need a civics class.
The First Amendment only applies to Congress (and, though I disagree with the USSC, to State Governments) restricting the Free Exercise of religion. I can restrict it all I want on my Private Property which should be obvious to you.
Because of essentially unrelated USSC decisions Clemson, being a Public University (i.e. a derivative of a State Government) cannot restrict "Free Exercise," but like shouting "FIRE," in a crowded auditorium, the right to "Free Exercise" can be limited in some ways. E.g. Muslims cannot chop off infidels heads.
ML/NJ
The right to life and liberty take precedence, so there really can be no ‘muslim right to behead.” It is an extreme example, but it doesn’t work given the provisions of the amendment that clearly are universal and not congressionally based. Unless, of course, someone would like to maintain that states can deprive of life and liberty at whim because they are not congress. That was made clear in the XIV “No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.”
“No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger; nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.”