Honestly, I don’t think they understand the symbols they used, but if they do this is probably what they mean.

The girl with the horns and the pentagram is just meant to be satanic. The owl is a symbol of wisdom and darkness, probably meant to represent Moloch; an owl god who expects human sacrifices and is worshipped by some American elites. The girl with many eyes is again a symbol of wisdom, probably meant to reference the all seeing eye and/or an angel. It’s hard to tell what kind of plant is in the painting, but it looks like white roses, best guess on this one is a reference to western ceremonial magick (specifically Rosicrucianism) and/or Alice in Wonderland. Finally, for a second at the end they are cutting a lamb shank, which is probably meant to be cutting up Jesus (the lamb of god), but is also ironically symbolic of eating the body of Christ in communion.

If I had to say an overarching theme it’s about sacrifices to Moloch, but again I don’t know if they really understand these symbols. They probably just wanted it to be creepy to Christians.