Suppose that a group of evil humans in a remote land gets together and smokes some psychedelic substances. Doing so puts them all into a state of altered consciousness. While in that state, they all suddenly see a towering being of light appear to them.
This being proceeds to tell them that he is the true god and that there is no other god besides him. The being is frog-like in appearance. The spirit being commands the men to make an image of itself and worship that image.
The being orders them to make the image to have three heads even though it only has one head. The men do so and originate an entire religion around the worship of their three-headed frog-like god.
Christian Refusal to Believe What Happened
Some Christians later come to the remote area where these idolaters live and see the idol. The Christians conclude that the people just used their imagination to make an idol that was somewhat like real frogs that they had seen somewhere in their land.
When they try to evangelize some of the idolaters, the Christians refuse to believe what the idolaters tell them had happened to guide them to make the idol. They reject their testimony that they really had seen a spirit being that was frog-like in appearance and that had ordered them to make that idol.
Would such Christians be right or wrong? According to Scripture, there are demons who are frog-like in appearance:
Revelation 16:13 And I saw three unclean spirits like frogs come out of the mouth of the dragon, and out of the mouth of the beast, and out of the mouth of the false prophet. 14 For they are the spirits of devils, working miracles, which go forth unto the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty.
Therefore, Christians who would refuse to believe such a testimony— if it were ever to be given to them—would actually be wrong in thinking that demons cannot appear to humans to guide the humans to engage in any such kind of creative activity that is of demonic origin.
An important conclusion follows from applying the dynamics of the story related above to the realm of instrumental music. Demons can easily influence evil humans in a similar manner to produce demonic music on instruments so that the music is of demonic origin and not solely a product of human imagination and creativity.