I agree that the type of music shouldn’t matter.

Why?

Electric Guitars are not any more of “demonic origin” (as often claimed by certain conservatives) than any “ancient soft-sounding traditional musical instruments” (in their respective cultures) which have probably been used in “demon worship” for perhaps “a few thousand years” (in the past).

Point?

The “musical instrument” (E.g. the electric guitar) itself is “not” demonic but rather “What purpose it is used for” which matters.

Also,

What’s important is the “meaning sung” (as accurate as possible, theologically speaking) and the “outward appearance” which doesn’t contradict the Bible (E.g. Men are “not” allowed to have long hair as specifically mentioned in the New Testament too – please see below):

“Does not even nature itself teach you that if a man has long hair, it is a dishonor to him,” (1 Corinthians 11:14)

Unless of course it’s allowed in “certain instances” such as “vows to God” (E.g. The Nazirite vow). So, a person quoting to follow after the Nazirite Vow or such Scriptural exceptions must keep them for if not, isn’t it taking (or quoting) the Name of God in vain?

Hence, even if they don’t follow such rules as “found or re-affirmed by Holy Scripture” to be observed under the “New Testament too” (please don’t quote an irrelevant abolished Old Testament rule as a counter analogy since I’m “only” quoting this from the “New Testament” meaning it’s “enforced even now”).

We don’t judge them (that’s up to God). We speak the Truth contained in Scripture and let each one decide for themselves whether to obey or not. That’s rationality.

However, any “appearance of evil” (even outwardly) should be “abstained from” (E.g. Images or concepts of murder, demons and of darkness are to be “avoided”) as it is written too that:

“from all appearance of evil abstain ye;” (1 Thessalonians 5:22)

I repeat, it’s “not” the music but the “appearance of evil” which we need to be careful of too.