Some religious people make statements, which from their point of view are correct, according to their beliefs. But very often those people are not really familiar with the subject they discuss. If someone knows bible it doesn't mean they understand Aikido even if they think they are right.
I had Adventists telling me that it was a sin to train on Saturdays (because you sweat and Saturdays are sacred). The best one was that 'all martial arts are idolatry because they come from China and they are all Buddhists there, aren't they?' I replied that the cup of tea that man was having while we had the conversation was also Buddhist, following his logic, as that tea came from India. To him it sounded ridiculous although his statement seemed true to him. I think they key word to this is ignorance.
As for they bowing to kamiza - you should know what's in your heart and what you mean by it. Apostle Paul said that some people do not eat certain food and do so for the Lord, others eat everything and do so for the Lord; and Paul didn't have a problem with either, as faith was not about keeping the Law to him.