The use of Gaia cards would be opening the door to evil because they are based in the occult art of divination.
For those who have never heard of them, Gaia cards come in the form of a 45-card deck and are used to divine the future and “find the answers you seek.”
The most popular cards in use today are the creation of an artist named Toni Carmine Salerno who posits a much different explanation of the creation of the universe than what Christian’s encounter in Scripture.
"Far back in time, light from the underlying fabric of creation burst forth creating the super-luminous event through which our Universe was born. Time began its endless journey through ever-expanding space. The early universe was simply a sea of particles floating through space and time. But life's invisible wheels were already in motion and over time the sea of particles became a sea of stars from which Gaia, our Earth, was born; a living, breathing entity; our Goddess, our Mother and our reflection. Gaia Oracle will point you in love's direction and help you find the answers you seek.”
The cards are said to offer guidance, affirmations and transformation to those who use them.
As this reviewer of the cards says, “I have found the Gaia Oracle deck to be very supportive and helpful in connecting with spiritual life on a daily basis.”
It’s important to point out that regardless of how “positive” and “supportive” the affirmations in these cards may sound, they are based on a belief in a Greek deity named Gaia, who is otherwise known as the Mother Earth goddess. Therefore, using these cards is a violation of the First Commandment - “Thou shall not have other gods beside me.” (Exodus 20:3)
Resorting to the occult art of divination is also strictly forbidden in Scripture.
“Let there not be found among you anyone . . . who practices divination . . . Anyone who does such things is an abomination to the Lord. . . ” (Deuteronomy 18:10-12)
Anytime a person turns to forces that are not sourced in God, they open the door to demonic entities which can begin to wreak serious havoc on their lives through more direct means such as in the form of infestation and/or oppression. The only way to shut this door once it has been opened is to personally renounce all involvement in these activities and repent of this activity before Jesus (for Catholics, this should be done in sacramental confession).