Cam, the 1st amendment is about the gov not making any church or religion the official state religion. It means you can't force people to tithe or endorse one faith or another in order to hold office. Its also about the protection of worshipers of either Jesus or Alah or whomever can do so without government interference. It doesn't mean that if you hold the belief that one faith is more true than another then you cannot serve on as a public figure. That's where Sanders was treading on thin ice. He essentially said "your religion, do you believe it to be more true than others?" and if the answer was yes then he was going to go after him a bit.
Do you want a representative that believes (contrary to the constitution) that one person is inferior to another based solely on religious belief?
The "thin ice" is when you legislate legal discrimination under the guise of "religious liberty"
of course not. I'm not sure where you're getting the word inferior from. If the conclusion that someone made was "my religion is more true, therefore other people are not due the the same rights etc. I am" then I would not want that person to serve.
I mean, this all started because the guy was arguing that a woman was justifiably fired solely because of her religious beliefs.
The woman fired was a Christian professor at a private, Christian college. She wore a hijab in the aftermath of the Paris and San Bernadino shootings in an effort to show solidarity with muslims and suggested that Muslims and Christians worship the same God. She was apparently placed on leave because of her vague statement on the theological relationship between Christians and Muslims.
In other words, it's not like her employer found out she was a Muslim and fired her for it. Her employer, a private religious college, disapproved of the message she vaguely sent which apparently contradicted the school's teaching.