[antiRepublicrat]

When I go to religious services of my Jewish in-laws, I don't care if they go "Hear O Israel the Lord your God is One".

I wouldn't care either. But you are not part of their congregation. For a chaplain, every religious person there is part of his congregation.

[muawiyah]

There is no "congregation" at the sort of meetings presided over by a chaplain.

A congregation necessarily consists of people of similar belief or ethnicity.