I was taught as a child that believing in astrology was a sin against the first comandment. It is believing in false gods. Please explain how believing in astrology is a sin against the first comandment.
Here’s what the Catechism of the Catholic Church says on the issue:
All forms of divination are to be rejected: recourse to Satan or demons, conjuring up the dead or other practices falsely supposed to “unveil” the future. Consulting horoscopes, astrology, palm reading, interpretation of omens and lots, the phenomena of clairvoyance, and recourse to mediums all conceal a desire for power over time, history, and, in the last analysis, other human beings, as well as a wish to conciliate hidden powers. They contradict the honor, respect, and loving fear that we owe to God alone (CCC 2116; emphasis added).
By placing trust and faith in various forms of divination, including astrology, a person is transferring to astrology the trust and faith that should be placed in God alone. When we give to someone or something else what can only be given to God, we are treating that person or thing as if it is a god. That is why astrology violates the commandment “Thou shalt not have strange gods before me [the one true God].”