I must say you have to have excellent screening abilities Refiners... I'd give my disgust away if I ever went anywhere like that, and I don't think standing up in the middle of a service and denouncing their crack-pot fantasy world would be very healthy... !
I grew up in a very multi-ethnic environment. About 95% of my JW friends as a teenager had parents from the Carribian. So, being in a group of black kids, I got some experience of racist attitudes, both towards black people and towards the friends of black people; the dirty looks, the mumbled words, the spitting... fortunately no outright violence, but disgusting behaviour all the same.
Unfortuantely, it means I am pretty untolerant of racists myself, and the idea of going to a white supremisist church makes my skin crawl. I've studied enough to know their position without needing to get involved... but I think I understand your point, even if it's not something I could do (for fear of turning up when the church was empty and torching it, which would be lowerting myself to their level).
I find the psychological profile of racist groups I've looked at and individuals I've met is normally such that they seek some higher authority - Hitler, eugenic 'science', mangaled scriptural justification, convoluted and unproven acceptance of shibboleths like the Zionist Conspiracy - to justify making an easily identifable group scape-goats for all societies ills.
It's a crock of shit, and is made worse by the fact the leaders of such movements are very aware of how powerful hate messages are when proseltysing their venom towards the disadvantaged. Look at the Aryan Brotherhood and American jails.
Xena; in American English coloured is spelt colored. In America, however you spell it, it is a bad word, associated with racist attitudes. That applies slightly less in England, as we never had offical or legal restraints to black peoples lives to the extent they had in the US, but generally older people are the only people who will use 'coloured' in place of 'black'. It's also compicated by the fact in England there is a large Asian community, chiefly from the Indian sub-continent, and although it is becoming increasingly acceptable to just use the term black just to mean non-white, it wasn't always so. In Australia, where Refiner hails from, I believe, 'blacks' tends to refer to Australian Aborigines. The amount of African black people is comparatively small, and the Asians are ususally from China/Japan/Korea/Vietnam etc., as distinct from India.
Thus the use of coloured is probably local usage and not racist in itself.