Dowsing is divination, whether you are using a stick or a crucifix, and divination is forbidden by God.
“No one shall be found among you who makes a son or daughter pass through fire, or who practices divination, or is a soothsayer, or an augur or a sorcerer, or one who casts spells or who consults ghosts or spirits, or who seeks oracles from the dead. For whoever does these things is abhorrent to the Lord . . .” Deuteronomy 18:10-12
This prohibition includes dowsing, an occult art associated with witchcraft that utilizes either a forked stick or pendulum to discern the presence of water, oil, lost treasure, or answers to questions about the future.
In fact, dowsing is explicitly forbidden in Scripture. “My people consult their wooden idol, and their diviner’s wand informs them; for a spirit of harlotry has led them astray, and they have played the harlot, departing from their God” (Hos. 4:12).
It is much too common a practice for Catholics to think they can “baptize” an occult art simply by incorporating a religious object into the mix. For instance, how many people think they can control the weather just by putting a Blessed Mother statue in the window? Scores of people bury St. Joseph statues thinking it will help them sell their homes. When we put our faith in these objects rather than in the saints who are represented by them, we engage in superstition.
In other words, it’s okay to pray to Mary for help with the weather, or to St. Joseph to help you sell your home, but just by placing statues on a windowsill or burying them in the ground is to affix some sort of magical power to the object, which is what makes it an occult practice.
The same holds true for attempting to use a rosary or a crucifix as a pendulum for the purpose of divining answers to our questions. This is divination and when we engage in it, we are resorting to the occult.
The occult pertains any system that claims to use or have knowledge of secret or supernatural powers or agencies. This includes witchcraft, alchemy and magick, palm reading, fortune-telling, tarot cards, ouija boards, and astrology. The occult also includes spiritualistic practices such as séances, channeling and mediumship, and out-of-body experiences such as astral projection.
The Catechism teaches us that resorting to divination for any reason “conceals 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.” (No. 2116)
For more information on dowsing, read /?p=146