What Rin said.
There is also more reason to/philosophy behind not allowing IC-racists in then simply not offending other members (and we don't want OOC-racists either, btw. >,>):
The goal is to portray the reasonable and maybe even sophisticated side of Amarr (religion). This rules out fanatics and racists as well for scientific and theological reasons. Fanatics are by definition unreasonable. Reacism is at its core a naturalistic/biologistic view that a) is at odds with the science of biology and b) eventually collides with any reasonable concept of God.
Therefore we expect to have better reasons/explanations/justifications for assuming whatever superiority of whatever people. In general the view pushed by the corp here is that Scripture already 'hints' at what makes people superior: Living a righteous life in fear of God. God didn't choose people for their race, but for their ethical qualities.
Thus SFRIM isn't opposed to a superiority theory (of the Amarr people) in general, but opposes simplistic explanations of the 'my blood is purer'/'my race is better' kind, which reek with self-contradictions and contradictions to good Amarrian cultural practice. They thus fit by far better heathens and heretics like the Bloodfriends - or other people who can't use their ability to reason. Concisely: Racism is a ideology that inferior people need to make them feel great, because they are unable to act in a superior way.
Of course, we don't expect that all our members burden their mind with such sophisticated theological thought. We have experts for that. Also, the Amarr consider orthopraxy to be more important then orthodoxy, after all.