[Roseate]

Thank you for your reply, BobK.

This is the context the sentence is from.
"... The result was the weight and waisline started coming down. I was also dieting religiously durng this period of time (I quit eating in church). Seriously, I did diet and I'll have more to say about that in a moment...."

This is extracted from See You At The Top, a book by Zig Ziglar (an American). He was doing things to lose his weight. Previously, he didn't say he had his meals in church, or anything like that, so I feel, if the sentence is not - and you say it isn't - an idiom, it'd make no sense literally. (wouldn't it be ridiculous to eat in church?)

I'm glad you've noticed my post anh shared your opinion anyway.

Roseate