The Word of God is clear when He says,
“When you come into the land that the Lord your God is giving you, you shall not learn to follow the abominable practices of those nations. There shall not be found among you anyone who burns his son or his daughter as an offering, anyone who practices divination or tells fortunes or interprets omens, or a sorcerer or a charmer or a medium or a necromancer or one who inquires of the dead, for whoever does these things is an abomination to the Lord. And because of these abominations the Lord your God is driving them out before you. You shall be blameless before the Lord your God, for these nations, which you are about to dispossess, listen to fortune-tellers and to diviners. But as for you, the Lord your God has not allowed you to do this” (Deuteronomy 18:9-14).
It should also be pointed out that since astrology is a form of divination it comes under the condemnation of the above passage. Furthermore, Christians are urged to entrust themselves and their lives to their all-powerful and gracious God, in whom the Psalmist places his heartfelt trust by declaring, “My times are in Thy hand” (Psalm 31:15; see Eccl. 7:14). Christians remember that neither the daily course of their lives nor their future lies in the hands of unseen forces or movements of heavenly bodies. Rather, they are urged to believe that everything in their life is directed according to His gracious purpose: “In everything God works for good with those who love him, who are called according to His purpose” (Romans 8:28; RSV). In light of these considerations, Christians who consult horoscopes “just for the fun of it” need to be aware of the spiritual dangers involved in such a practice.
Finally, Luther explained the Second Commandment (“You shall not misuse the name of the Lord your God”) in this way: “We should fear and love God so that we do not curse, swear, use satanic arts, lie, or deceive by His name, but call upon it in every trouble, pray, praise, and give thanks.” The explanation in the catechism further states that using “satanic arts by God’s name” includes “depending on horoscopes or similar ways to foretell the future.” Thus, using horoscopes is included among sins against the Second Commandment.