Ask any theologian: Modern Christianity and superstition cannot coexist. Quite simply, belief in one excludes belief in the other. Yet many of our surviving superstitions were born from religious beliefs. Take a look:
Black cats -- There is much mystery and magic associated with cats, especially those the color of the night, when the forces of evil are strongest. The cat was once considered sacred to the Egyptian goddess Isis and thus worshiped and prized.
It wasn't until centuries later that black cats were deemed evil by early Christians who thought they represented the devil. It was this association with evil that led Europeans during the Middle Ages to believe the black cat to be a companion of witches, even a witch's other self (when a witch took the form of a cat).
There's a tale told in Lincolnshire, England, of a father and son who one day came across a black cat. Suspecting it to be a witch, they stoned it. The next day, the father and son saw the witch in human form. Her face was bandaged, and she died soon after. Creepy . . . if you believe.
Friday the 13th -- The number 13 has been considered unlucky since the Greek philosophers thought they had discovered mathematical relationships permeating the universe. When represented by dots, 13 cannot be arranged symmetrically.
More common, dread of the number 13 dates back to the Last Supper of Christ, where there were 13 at the table. Fear of Friday is also associated with Christ. Early theologians believed Christ was crucified on a Friday.
Walking under a ladder -- A ladder leaning against a wall forms a triangle, one of the strongest symbols of the Holy Trinity. Anyone who walks through this sanctified space risks divine wrath.
Knock on wood -- One story dates to the days when people lived in wooden huts; when speaking of their good fortune, the people would knock loudly on the walls to keep the gods from overhearing and becoming jealous.
More likely, however, the superstition comes from pagan times, when trees were deified. When lightning bolts struck a tree, people thought a divine power had entered it. To touch the tree, then, would transfer power and good luck to themselves.
Spilled salt -- From earliest times, salt was a holy symbol of life and a precious commodity. The Greeks and Romans mixed salt with their sacrificial cakes. Salt was rare and expensive; to lose some by carelessly spilling it was economic disaster.
Because of the good that salt represented, the devil enjoyed seeing it wasted. But a pinch of salt, tossed over the left shoulder -- the side the devil stays behind -- could prevent him from doing harm.
Broken mirror -- This dates back to the days when mirrors could not be broken. The first mirrors were pools of water. People looked in them to foresee their fate. If their reflection was disturbed, it was a sign that ill luck was to befall them. Later, man believed that a person's reflection was the soul, independent and removed from the body. If the mirror was shattered, the soul, too, was shattered. Death was soon to follow.
Rabbit's foot -- Early hunters found the rabbit hard to capture, difficult to spot and quick to get away. This, along with the rabbit's reproductive prowess, caused people to associate it with prosperity. When a rabbit was caught, its captor would boast of his conquest, proving his prize by showing off the rabbit's food. It wasn't long before people believed the rabbit's foot was a lucky charm. Of course, it wasn't too lucky for the rabbit, was it?