Ritual purification is a feature of many religions. The aim of these rituals is to remove specifically defined uncleanliness prior to a particular type of activity, and especially prior to the worship of a deity. This ritual uncleanliness is not however identical with ordinary physical impurity, such as dirt stains; nevertheless, all body fluids are generally considered ritually unclean, and some religions have special treatment of semen and menses, which are viewed as particularly unclean.
Most of these rituals existed long before the germ theory of disease, and figure prominently from the earliest known religious systems of the Ancient Near East. Some writers remark that similarities between cleansing actions, engaged in by obsessive compulsive disorder sufferers and those of religious purification rites, point to an ultimate origin of the rituals in the personal grooming behaviour of the primates, but others connect the rituals to primitive taboos.
The Hebrew Bible has many rituals of purification relating to menstruation, childbirth, sexual relations, Keri (Nocturnal emission), unusual bodily fluids, skin disease, death, and animal sacrifices. Modern mainstream Judaism is based on a combination of the Hebrew Bible and Jewish oral law, which includes the Mishnah and Gemarrah (together comprising the Talmud) in addition to other rabbinic commentaries; this oral law further specifies regulations for ritual purity, including obligations relating to toiletary functions, meals, and waking. The regulations of biblical and oral law generally prescribe a form of water-based ritual washing in Judaism for removal of any ritual impurity, sometimes requiring just washing of the hands, and at other times requiring full immersion; the oral law requires the use of living water for any ritual full immersion - either a natural river/stream/spring, or a special bath (a Mikvah) which is directly connected to one.
These regulations were variously observed by the ancient Israelites; contemporary Orthodox Jews and (with some modifications and additional leniencies) some Conservative Jews continue to observe the regulations, except for those tied to sacrifice in the Temple in Jerusalem, as the Temple no longer fully exists. These groups continue to observe many of the hand washing rituals. Of those connected with full ritual immersion; perhaps the quintessential immersion rituals still carried out are those related to nidda, according to which a menstruating woman must avoid contact with her partner, especially avoiding sexual contact, and may only resume contact after she has first immersed herself fully in a mikvah of living water seven days after her menstruation has ceased. Chabad-Lubavitch and some other Hassidic groups practice daily ritual immersion.
In December 2006 the Committee on Jewish Law and Standards of Conservative Judaism re-affirmed the traditional requirement that Conservative women ritually immerse following menstruation. In doing so, it adopted multiple opinions regarding details, including an opinion reaffirming traditional (Orthodox) practices and concepts, an opinion adapting certain leniencies including counting seven days from start of menstruation rather than its end, and an opinion reformulating the theological basis of the practice, basing it on concepts other than ritual purity. See the Niddah article for details. Classical ritual immersion and associated requirements are generally not observed by Reform Judaism or Reconstructionist Judaism, with the exception that both generally include immersion as part of the ritual for Conversion to Judaism, although Reform Judaism does not require it.
Baptism, as a form of ritual purification, occurs in several religions related to Judaism, and most prominently in Christianity; Christianity also has other forms of ritual purification. In older churches, and modern Roman Catholic churches, there are a number lavers around the building for the laity to use as ritual symbolism of cleansing themselves, usually by dipping the fingertips in the holy water, and then making the sign of the cross. In traditional liturgical churches a laver, often embedded in the wall, exists for the priest and deacon to wash their hands before celebrating the Eucharist, and to pour any excess Eucharistic wine onto natural earth, to which the outflows of these lavers connect.
Many ancient churches were built with a large fountain in the courtyard. It was the tradition for Christians to wash before entering the church for worship. This usage is also legislated in the Rule of St. Benedict, as a result of which, many medieval monasteries were built with communal lavers for the monks or nuns to wash up before the Daily Office.
Traditionally, Christianity adhered to the biblical regulation requiring the purification of women after childbirth; this practice, was adapted into a special ritual known as the churching of women, for which there exists liturgy in the Church of England's Book of Common Prayer, but its use is now rare in Western Christianity. The churching of women is still performed in a number of Eastern Orthodox, Oriental Orthodox and Eastern Catholic churches.
Roman Catholics, Eastern Orthodox and High church Anglicans are also traditionally required to regularly attend confession, as a form of ritual purification from sin, especially as preperation before receiving the Eucharist. However, this is only required once a year or if a mortal sin has been committed.
Islamic ritual purification is particularly centred on the preparation for ritual prayer; theoretically ritual purification would remain valid throughout the day, but is treated as invalid on the occurrence of certain acts, such as sleep, contact with the opposite gender, unnconsciousness, and the emission of blood, semen, or vomit. According to Ibn Hazm (994-1064), who has discussed the subject in detail, there is not a single verse of the Qur'an nor any authentic hadith stating that a state of ritual purity is a pre-requisite for touching the Qur'an; however, all the schools of thought universally agree that ritual purity is preferable prior to contact with the book.
Ritual purification takes the form of ablution, in a lesser form, and greater form, depending on the circumstance; the greater form is obligatory by a woman after she ceases menstruation, on a corpse that didn't die during battle, and after sexual activity, and is optionally used on other occasions, for example just prior to Friday prayers, or entering ihram. An alternative dry ablution, involving clean sand or earth, is used if clean water is not available or if suffering from an illness which would be worsened by the use of water; this form is invalidated in the same circumstances as the other forms, and also whenever water becomes available and safe to use.
The obligatory activities of the lesser form include washing of the feet arms and head, while some optional acts also exist such as recitation of the Basmala, recitation of the Shahadah, and/or brushing of the teeth; the greater form includes the acts of the lesser form, as well as ensuring that the entire body is washed. Many details of Islamic ritual purification vary between as well as between the different divisions of Islam and between the different schools of thought within each division.
In the Bahá'í Faith, ritual ablutions (the washing of the hands and face) should be done before the saying of the obligatory prayers, as well as prior to the recitation of the Greatest Name 95 times. Menstruating women are obliged to pray and fast, but have the alternative of reciting a verse instead of the obligatory prayer; if the latter choice is taken, ablutions are still required required before the recital of the special verse. Bahá'u'lláh, the founder of the Bahá'í Faith, prescribed the ablutions in his book of laws, the Kitáb-i-Aqdas.
That ablutions have a significance beyond washing, and should be performed even if one has bathed oneself immediately before reciting the obligatory prayer; fresh ablutions should also be performed for each devotion, unless they are being done at the same time. If no water is available, or when clean water is not available or when suffering from an illness which would be worsened by the use of water, then one may instead repeat the verse "In the Name of God, the Most Pure, the Most Pure" five times before the prayer.
Various traditions within Hinduism follow different standards of ritual purity and purification; in Smartism, for example, the attitude to ritual purity is similar to that in Orthodox Judaism. Within each tradition the more orthodox groups follow stricter rules, but the strictest rules are generally prescribed for brahmins, especially those engaged in the temple worship.
An important part of ritual purification in Hinduism is the bathing of the entire body, particularly in rivers considered holy such as the Ganges; it is is considered auspicious to perform this form of purification before any festival, and it is also practised after the death of someone, in order to maintain purity. Although water pollution means that in modern times there is a need for care during bathing in such rivers, the physical impurities within the river do not diminish the attributed power they have to bring ritual purity. Lesser aspects of Hindu purification ritual include achamana - the touching and sipping of pure water while reciting specific mantras - and the application of a tilaka on the forehead.
In the ritual known as abhisheka (Sanskrit, "sprinkling; ablution"), the deity's murthi or image is ritually bathed with water, curd, milk, honey, ghee, rosewater, etc. Abhisheka is also a special form of puja prescribed by Agamic injunction. The act is also performed in the inauguration of religious and political monarchs and for other special blessings.
In Shinto, the main form of ritual purification is Misogi, which involves natural running water, and especially waterfalls. Rather than being entirely naked, men usually wear Japanese loincloths, and women wear kimonos, both additionally wearing headbands.
In the traditions of many Indigenous peoples of the Americas, one of the forms of ritual purification is the ablutionary use of a sauna, known as a sweatlodge, as preparation for a variety of other ceremonies. The burning of smudge sticks is also believed by some indigenous groups to cleanse an area of any evil presence.