Red in liturgical settings is used two ways...for martyrs, and on Pentecost, when the Holy spirit came in tongues of fire.
This long predates the nazis.
Satanists might be copying this as a way to insult the Lord, like the rainbow, but that doesn't mean it is the same...it has ancient Christian meaning.
Thank you for your post.
I think you are correct and whether intended or not that is what they are doing. Personally I like the colors red and purple created by God as part of his gift to us and resent the evil ones trying to take them from us.