One reason Christians shouldn’t practice astrology is, quite simply, because the Bible tells us not to. Astrology and other forms of fortunetelling were very common in the ancient world, but the Bible writers called them “detestable practices” (Deuteronomy 18:12).
Christians don’t follow astrology because we don’t need to. God has given us everything we need to know about the future in His Word. Of course, the Bible doesn’t tell us what will happen next week or next year; if if did, we would never learn to trust God or seek His guidance.
The heavens declare the glory of God; the skies proclaim the work of his hands.
Billy Graham – Wisdom For Each Day