Christ is also referred to as the "morning star". Satan isn't [necessarily] "evil", it is the other side, the rival, of God.
Just because astrology exists in the Bible, doesn't mean that's all it is.
Satan lies dead in matter, until we make it alive with our life (spirit) by becoming its servants. When satan (the law, spirit, of matter: cooling off, paralysis, drawing inward) acts in matter (its right place and time), it is a divine law, but when it is in our mind, we become it, and the law turns into mental forms and we become cold and hard and self-centered, just like matter.
Spirit is life, matter is resistance. The law of the spirit is radiation, giving, selflessness.