People should be employed on their ability to do the job (part of which will be interaction with others). If their religious beliefs impact on their ability to do the job or their interaction with others then you would have a valid and justifiable concern. I work with many muslims (as an example) who do an excellent job (better than me) and have no personal interaction problems. So why should their beliefs be of concern to me? It seems to me that you are putting your beliefs about their beliefs at the front of your mind.