I've never seen questions like this here, and I'm wondering if this is something that the community would feel is on-topic, so long as it remains constructive and objectively answerable. If not, no hard feelings, but here goes...
Many of the hymns sung in our Churches are filled with deep theological meaning and doctrinal statements in and of themselves. For example, take "Amazing Grace". It includes:
- The doctrine of undeserved Grace, given to a wretch "like me"
- A hint of what repentance looks like (understanding myself to be a wretch, which I certainly am.)
- Spiritual blindness and how Grace opens our eyes to see spiritual truth
- God's Grace is necessary before we can even see our lost state - How Grace teaches us that we are lost sinners and convicts us
- And of course, how Grace, once we have been given it, means that we are now found
- The message that life in Heaven is eternal - after ten thousand years of singing God's praise, we'll still have no less days to look to in the future.
And on and on, in that one song alone.
With the wide variety of denominations, teachings, doctrines, heresies, and truths out there, how much more could we be learning from each other just by analyzing the hymns we sing. Certainly there are hymns that are more common in protestant denominations than in Catholicism, and my memory is completely failing me on this one, but I'd bet the LDS Church has unique hymns that can help illuminate doctrine that most of us just take for granted when singing the hymns.
So would a question like "What doctrines are taught in the Hymn Amazing Grace" be on-topic?
It certainly could be answered objectively, and certainly could be a new field of questions that can enrich us beyond mere academic analysis. Bringing song and culture into the mix could be, IMO, a good thing, if we don't allow it to balloon into the non-constructive and silly.