In Hindu culture, the feet are considered the lowest, most impure part of the body.  Feet and shoes are farthest from the heavens, and in constant contact with the dirt of the earth.

The feet and shoes are the source of many potential insults in Hindu culture.  When sitting, Hindus are not to point their feet at someone.  In a temple, they are not to spread their feet toward the altar or their fellow worshippers.  It is a supreme insult and show of contempt to throw a shoe at a person.  (Of course this isn’t limited to Hindu or Indian culture.  Recall the famous incident when an Iraqi protester insulted President Bush by throwing his shoes at him.)

If a Hindu inadvertently touches someone with their shoe, they are to immediately indicate that no offense was intended by lightly touching with their right hand the spot on the person where the shoe made contact, and then with the same hand touching their left eye and then right eye while apologizing.

One acknowledges one’s inferiority and shows respect by initiating contact with someone’s feet.  For a person to touch the feet of a guru or elder, for students to touch the feet of their teacher, or for children to touch the feet of their parent is a gesture of obeisance.  Some temples contain shoes meant to represent the feet of God, which worshippers touch to their forehead.

To indicate that even the lowest part of an honored person’s body is sacred, the feet of God or the holiest of people are referred to as “lotus feet.”

Because shoes are on the lowest part of the body and accumulate dirt and impurity - physical dirt, but also a supposed spiritual dirt or negative energy from the earth - it is a sign of respect to refrain from wearing them indoors and bringing this impurity inside.

Thus footwear is not worn inside temples.  In smaller temples, shoes are simply left outside along the wall before entering.  In some temples, there is a special area with shelves for shoes.  In certain temples in cold climates a partial exception to this rule is made in winter.  Special wooden shoes are provided to wear only inside the temples.  So the worshippers must exchange the impure shoes they have worn outside for the special temple shoes, and then exchange back when leaving the temple.

Most Hindus extend this practice to private homes as well, taking off their shoes before they enter their home or the home of a fellow Hindu.  Even carrying shoes in one’s hands from room to room indoors is to be avoided.

In some Indian villages, it is customary for women to drink from a holy shoe in order to ward off evil spirits.

The consistent thread that runs through Hindu tradition about the feet and shoes is that contact with the lowest part of the body is an indication of lower status, either accepted voluntarily as a sign of deference, or imposed upon one as an insult.

Sources:

“Frequently Asked Questions About Hinduism”

“Hindu Culture”

“A Hindu Primer”