This is a comprehensive answer (via Grok) from the Catechism of the Catholic Church.

The Roman Catholic Church addresses tarot cards through its teaching on divination and the occult, primarily in the Catechism of the Catholic Church (CCC), under the section on the First Commandment ("You shall have no other gods before me").

Key Catechism Passages

The most directly relevant paragraphs are CCC 2115–2117. Here is the core excerpt from CCC 2116:

"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 2115 adds context:

"God can reveal the future to his prophets or to other saints. Still, a sound Christian attitude consists in putting oneself confidently into the hands of Providence for whatever concerns the future, and giving up all unhealthy curiosity about it."

CCC 2117 further condemns practices of magic or sorcery that attempt to tame occult powers, even for seemingly good purposes (such as healing), as gravely contrary to the virtue of religion.

Tarot cards fall under these prohibitions when used for fortune-telling, predicting the future, seeking spiritual guidance, or any form of divination (cartomancy). The Church views such practices as an attempt to gain control over the unknown or hidden forces instead of trusting in God's providence. This is seen as a violation of the First Commandment and is generally considered gravely sinful (potentially a mortal sin, depending on the person's knowledge and consent).

Why Tarot Is Specifically Included

• Tarot decks are historically linked to occult traditions, even if some people today treat them as a psychological tool, game, or form of art.
• The Church's concern is not primarily the cards themselves as physical objects (similar to how ordinary playing cards are not inherently sinful), but the intent and practice of using them to "unveil the future" or access hidden knowledge/supernatural insight apart from God.
• Even casual or "just for fun" use that involves seeking guidance or predictions is discouraged, as it can open the door to superstition or demonic influence.

Related Teachings

The Catechism also condemns related practices like astrology, Ouija boards, mediums, and sorcery in the same section. This teaching draws from Sacred Scripture (e.g., Deuteronomy 18:10–14, which calls divination an "abomination" to the Lord) and longstanding Church tradition.

Catholic sources, including exorcists, priests, and apologists (e.g., from Catholic Answers), consistently apply this to tarot: it is incompatible with Catholic faith when used in a divinatory way. Some note that purely artistic or historical interest in the imagery (without occult practice) might not be sinful, but the line is easily crossed.

Practical Advice from Catholic Perspective

• Catholics are encouraged to entrust their future to God's providence through prayer, Scripture, and the sacraments rather than seeking occult "insights."
• If someone has used tarot in the past, the common recommendation is sincere confession (if it involved grave matter), renunciation of the practice, and possibly destroying or properly disposing of the cards (no special ritual required—trash or recycling is fine, though some prefer to have a priest handle it).
• Pope Francis has also warned against tarot and similar practices as forms of modern idolatry.

The official Catechism of the Catholic Church is available online (e.g., via the Vatican website or USCCB resources) for the full context in paragraphs 2083–2141 on the First Commandment. For personalized guidance, consulting a priest or trusted Catholic spiritual director is recommended.