It is quite true that I have often gone through great lengths to comment on people's reasons for religious beliefs and using pseudo-science to justify these beliefs. A belief in a higher power is just that - a belief. However, this is not about the reasons for the belief, but rather the actions that stem from that belief, and here I applaud those who remain true to their convictions.

Elsewhere, I questioned vegetarians whose reasons are of the environmental and moral types. This is certainly not the reasons behind all of those who are vegetarian. Many religions have dietary constraints placed on them ranging from the slight (no meat on Fridays during Lent other than fish) to strict (the vegetarianism of the Hindu Brahmin and Buddhist). Their reasons for the dietary restriction cannot be criticized.

Christianity
Most notably, this occurs with Lent - the period between Mardi Gras and Easter. Individual traditions vary within the various branches of Christianity.

Within the Eastern Orthodox church (Greek, Russian, Serbian, etc... as opposed to the Roman branch of the Christian church), a distinction between abstinence and fasting is made. To fast is to have no solid food between midnight and noon, while abstaining is no eating of meat, dairy, eggs, alcohol, fish, or olive oil. The requirement states that the first day of Lent is a day of fasting and abstinence, all Fridays are days of abstinence, and Good Friday is a day of fasting and abstinence. The devout even go another step and consider every week day of Lent a day of fasting and abstinence. This is often extended to all Wednesdays (not just in Lent) to be days of abstainence - restricting meat, dairy, eggs, fish, alcohol, and oil. In monastaries Mondays are sometimes also kept this way in honor of the "Fleshless Ones" in remebrance of angels (this comes from the liturgical theme of mondays and angels).

Throughout the Bible, there are plenty of examples of fasting, both in the New and Old Testaments. In Acts, it was clear that the Apostles kept every Wednesday and Friday as days of fasting and abstinence.

For more reading, please see Fasting in the Orthodox Church

Judaism
Many people are familiar with the concept of kosher (from the Yiddish, kasher from Hebrew). It is the opposite of terefah (forbidden) when applied to food. 'Terefah' originaly refers to 'flesh torn by an animal' (as used in Exodus 22:31), however over the past few thousand years, the meaning has extended to cover impure and forbidden foods. With dietary laws, it has a number of sources in the Old Testament:
  • It is not from animals, birds or fish prohibited in Leviticus 11 or Deuteronomy 14 (more about the specifics of fish can be found at Kosher Fish). Realize that almost all insects are unclean (its in Leviticus 11:21-22) and thus care must be taken to clean fruits and vegetables throughly before eating. (stand/alone/bitch notes that it is a pain to wash and check broccoli)
  • The animals have been killed in the ritual method of shehitah.
  • The meat has been salted to remove the blood (Deuteronomy 12) after the carcass has been examined for blemishes and a nerve has been removed from the hindquarters (Genesis 32)
  • Meat and milk have not been cooked together (Exodus 23) nor have the same utensils have been used.

The restrictions on diet are even more critical during Passover. Foods that meet these standards are Kashe la-Pesach meaning "fit for Passover".

Kosher wine is prepared under supervision to make certain that no idolatry has taken place and by extension, not handled by gentiles. The restrictions on wine are from the days of Rome when wine was often 'blessed' by Bacchus and were common to both Judaism and early Christianity. See Kosher liquor and spirits for a further discussion of this (and yes, Tequila is kosher, if there was no worm in the bottle).

Human flesh is not kosher.

While many cultural researchers have made efforts to link the restrictions of being kosher to prohibiting food poisoning and preservation of food in ancient times, the fact of the matter is that for the Jewish people, God has stated that this is the correct way to live.

Much of the rules around kosher food and practices is that Judaism forbids inflicting unnecessary pain and suffering upon animals. One of the easiest ways to maintain this is to be vegetarian. With few exceptions (fruits harvested on the shabbat or during shmita, for example), all foods that are vegetables are kosher. If uncertain if something is kosher or not, see kosher symbols.

Islam
Islamic dietary law prohibits pork or alcohol (this concept mirrors that of kosher and is called halal - unacceptable food is haram) and requires fasting during the month of Ramazan. The passage from the Koran that states this reads:

Forbidden to you (for food)
Are: Dead meat, blood,
The flesh of swine, and that
On which hath been invoked
The name of another than Allah;
That which hath been
Killed by strangling,
Or by a violent blow,
Or by a headlong fall,
Or being gored to death,
That which hath been (partly)
Eaten by a wild animal;
Unless ye are able
To slaughter it (in due form);
That which is sacrificed
On stone (altars);
(Forbidden) also is the division
(Of meat) by raffling
With arrows: that is impiety.
But if anyone is forced
By hunger, with no inclination
To transgress, Allah is
Indeed Oft-Forgiving,
Most Merciful.

Source: Sura 5, al-Ma'idah (Meal), Ayah 3. Holy Qur'an. Text, translation and commentaries by Abdullah Yusif Ali. Amana Corporation, Brentwood, Maryland, 1989, pp. 244-245 (in English)

It should be noted that Islam and Judaism have similar backgrounds and the restrictions on haraam foods has some similarity to kosher food, especially the method of killing is similar to the shehitah. See Halal meat for an indepth look at the subject of Halal and how it applies to food (paticularly meats). The similarity of food laws often means that muslims can find aceptable food in a store that caters to jewish people (a jewish butcher shop for example). This is most useful when traveling abroad and uncertain of the food there.

Hinduism
  • Scriptural law mandates non-injury. This is the first and foremost rule in the religious obligations as defined by Vedic scripture.
  • Hindus also believe in karma and the cycle of life and death. By eating another creature and causing that creature suffering, our future experience will have an equal measure of the suffering that has been caused. This can certainly add up.
  • To attain Nirvana, the eating of animals (meat, fish, shellfish, fowl and eggs) brings into the spirit the more mundane nature of the animal and the emotions felt as the animal died as it was butchered.

Buddhism
"To become a vegetarian is to step into the stream which leads to Nirvana"
--Buddha
Buddhists do not eat any food of dead animals. This does not prohibit the use of milk, however animal oils are prohibited. (I stand corrected - see below) Side note - Buddha was not a vegetarian.

Much more information than I could possibly incorprate into this node exists at Buddhist vegetarians.

The Church of Jesus Christ of Latter-Day Saints
While I have covered Christianity above, the Church of Latter-day Saints (also known as the Mormons) have dietary restrictions as part of every day life. Most notably, they do not drink tea, coffee, or liquor. Furthermore, they are not allowed to smoke. This comes from the Word of Wisdom and the prohibition on eating or drinking anything that contains a habit forming drug. Alcohol use is restricted to wine for sacramental use (it is prefered to use water for religious purposes instead, thus removing alcohol consumption all together) and strong alcohol for washing and cleansing. Eating meat is discouraged and emphasis is placed on the use of grains (especially wheat) and fruits and vegetables in season.

See also: Mormons and Caffeine for a discussion on that paticular aspect of Mormon dietary law.

Sikhism
At the time of the original writing of this node I did not touch upon many of the religions that have grown out of Asia. It is a rather daunting task. However, some information can be found at Jhatka meat.

The important thing to realize throughout all the examples above is that the reason is simple - God, Buddha, Allah, etc... has set forth these rules. It may be the case that they help an individual live longer, or remain more physical fit. It could be that in ancient times that it helped avoid food poisoning or aided in preservation of food. Whatever the case, this is not important to the members of the religions mentioned. What is important is that this is the way that they have been instructed to live and as examples of faith and piety.

No other reason is necessary.