When I mention Satan, I'm not talking about an individual entity, but rather a mindset. That mindset is a hatred of God and all things beautiful and good. Materialists, particularly those who spread the materialist mindset, are promoting the idea that there is no spiritual reality, no God, no ultimate good. In this way they are assisting the forces of darkness that would like the human race to turn away from the light of God and become increasingly rebellious and decadent. These forces would like to see humans become increasingly animalistic. The reason for this is that these forces of darkness feed off the chaotic emotions that this degenerate state produces. Of course, most materialists are unaware of this process as they really don't believe in the psychic or mental realm, just the realm of matter, therefore in that worldview there can be no dark spirits feeding off the emotions generated by the human race.
The idea that humans are just evolved apes is part of the effort to degrade the human race and steal the light from them. The alternative view is that humans are spiritual beings made of light and pure in essence. Of course, this purity is assaulted when one incarnates on earth due to the harsh conditions found here. On earth, many humans have fallen to a very low spiritual level/state of consciousness due to their submergence into the base desires of the physical body and their disconnection and disbelief in the higher virtues of the human spiritual being. Materialism encourages this process by saying we are just animals and there is nothing more to strive for than satisfying our bodily urges. In this way humans lower themselves without thinking that it matters. After all, there is no God, no ultimate good and no heaven. So what is there to strive for? In this way materialism supports the cause for darkness in promoting the degradation of the human spirit.