That is true, and yet another indication of how far our current government has strayed from the intent of the founders. There is an entire federal and state bureaucracy devoted to litigating cases against employers who dare terminate someone for expressing a particular "protected" opinion.
You will surely be on the losing side of most battles in that case. The vast majority of businesses are pro gay marriage now., or at the very least they don’t want people spouting off about it.
That sounds like a free society for the businessman and not so free for anyone else.