Maybe so, maybe not, I don't know enough Old Firm fans to comment and be so sure that the majority (extreme majority is what I guess you are insinuating) are religious bigots. never been close enough, i.e. lived in Glasgow, been to games, etc.
I have been to one Ibrox game with my mate and it is was fine, heard nothing bigoted or abusive (OK wasn't an old firm game as I am sure that creates a lot more tension than a random European home game that I went to), in fact there were signs saying that anything abusive or sectarian would automatically mean a ban, etc. Also, went to the UEFA Cup/Europa League final when they played Zenit in Manchester. Wore my Everton shirt and around the ground and in the ground only saw good people enjoying themselves. Even a few, who didn't have tickets, were talking to me (Non Rangers fan with a ticket) were joking around and being really friendly. I know there was trouble in the city centre and that is unacceptable, I suppose we can generally go on personal experience and I have never had any problems with them or Celtic fans, in my limited experiences.
What personal experience have you had, I know you absolutely detest them and that is generally spawned from personal experience, apologies if you have mentioned it before. Realise that may sound like I am trying to catch you out but generally interested in what makes you so angry at them as a group?