No because they identify their club through religion and denounce the other for the same reason. That's why they're bigots. The flags are just a way of giving their religion a 'homeland'.
I've always followed Celtic and am an Agnostic. I couldn't care less if someone believes in the trinity or not.
For me as a plastic, Celtic have always been a symbol for the migrated Irish population (you may disagree.........but it's a personal thing).
As for the pro-provo chanting, it's something I abhor and am very aware of.
I follow them as many posters on here would follow their national team. They're nowhere near as important to me as Aston Villa, but if i'm in a bar on a Sunday afternoon and Celtic are on, I will watch them and hope that they will win.