I am starting to doubt what people mean by NSFW.
Is the bible not appropriare for children? Some passages are certainly a little tricky, one may fall on one side or the other on the issue, but it's a discussion that reasonable people might have.
Is it Not Safe For Work? I don't think so.
What does proselytizing have to do with anything? Is that why porn is considered NSFW?
Will it cause problems if you are caught watching porn on your phone in the cafeteria during lunch break? Yes, unless you literally work at Brazzers.
Are you going to be disciplined for reading the Bible in the cafeteria during lunch break? Well I would hope not.
Most of the objectionable things that can be found on the Wikipedia entry for say, the Waco siege, or some random war reportage.
NSFW did not use to mean "not for minors". There are plenty of things unsuitable for children that won't raise anyone's eyebrow among your colleagues.