Generally speaking murder ballads tend to be a bit disapproving of fellas who kill their girlfriends or whatever; and Year of Jubilo is celebrating the end of slavery.

So those analogies don't really work.

I tend to feel that, if in some sense you don't mean what you sing, you shouldn't really sing it. "In some sense" allows for a lot of latitude. You don't have to be "a believer" to be able to sing a song from a religious tradition, your own or other peoples, and be sincere about it, because there are so many layers in religious traditions with which it is possible to identify from outside, and even when you maybe disagree sharply with other aspects.

The best thing people with a strong set of beliefs - religious or political for that matter - can do is, surely, to be self-evidently good and trustworthy people, so that their friends might want to find out what makes them tick. Imposing sermons or political speeches on other people isn't the way to do it.