It depends on what you mean by "demon." IMO demons are just spirits in darkness/ignorance / immature/aggressive/destructive/evil spirits, but not categorically different from non-demons. Given enough time a demon will get over that phase and grow into a decent spirit. So if it's somehow proven that demons are categorically different, that would change my mind about that. But it raises questions about in what way, and why, they're categorically different, why they exist, etc., and the answers to those would have further impact on my worldview.