Apostasy in the context of "Anti-paganism policies of the early Byzantine Empire"

Apostasy in Islam (Arabic: ردة, romanized: ridda or ارتداد, irtidād) is commonly defined as the abandonment of Islam by a Muslim, in thought, word, or through deed. It includes not only explicit renunciations of the Islamic faith by converting to another religion or abandoning religion altogether, but also blasphemy or heresy by those who consider themselves Muslims, through any action or utterance which implies unbelief, including those who deny a "fundamental tenet or creed" of Islam. An apostate from Islam is known as a murtadd (مرتدّ).

While Islamic jurisprudence calls for the death penalty of those who refuse to repent of apostasy from Islam, what statements or acts qualify as apostasy, and whether and how they should be punished, are disputed among Muslim scholars, with liberal Islamic movements rejecting physical punishment for apostasy. The penalty of killing of apostates is in conflict with international human rights norms which provide for the freedom of religions, as demonstrated in human rights instruments such as the Universal Declaration of Human Rights, the International Covenant on Civil and Political Rights, and the International Covenant on Economic, Social and Cultural Rights provide for the freedom of religion.Until the late 19th century, the majority of Sunni and Shia jurists held the view that for adult men, apostasy from Islam was a crime as well as a sin, punishable by the death penalty, but with a number of options for leniency (such as a waiting period to allow time for repentance or enforcement only in cases involving politics), depending on the era, the legal standards and the school of law. In the late 19th century, the use of legal criminal penalties for apostasy fell into disuse, although civil penalties were still applied.

Marital conversion is religious conversion upon marriage, either as a conciliatory act, or a mandated requirement according to a particular religious belief. Endogamous religious cultures may have certain opposition to interfaith marriage and ethnic assimilation, and may assert prohibitions against the conversion ("marrying out") of one their own claimed adherents. Conversely, they may require the marital conversion of those who wish to marry one of their adherents.

Religious offenses are actions that are considered to violate religious sensibilities and arouse negative emotions in people with strong religious beliefs. Traditionally, there are three unique types of acts that are considered to be religious offenses:

• Heresy (wrong choice) means questioning or doubting dogmatic established beliefs.
• Blasphemy (evil-speaking) is the act of insulting or showing contempt for a religious deity.
• Apostasy (revolt or renunciation) implies the abandonment of a prescribed religious duty (i.e. disloyalty, sedition or defection)

Individuals in any given religious community may be sensitive to different things in different measures, particularly in relation to topics such as sexuality, infancy, society, and warfare. Religious offense can be caused deliberately or motivated by religious intolerance, especially between specific religious beliefs regarding "sacred truth". However, every religion is essentially a set of beliefs conveyed from generation to generation which are, by religious definition, held to be immutable truths by that religion's believers or followers. Anything that tends to weaken or break that chain of authoritative continuity is likely to be deemed offensive and, in some jurisdictions, severely punishable.

European witchcraft can be traced back to classical antiquity, when magic and religion were closely entwined. During the pagan era of ancient Rome, there were laws against harmful magic. After Christianization, the medieval Catholic Church began to see witchcraft (maleficium) as a blend of black magic and apostasy involving a pact with the Devil. During the early modern period, witch hunts became widespread in Europe, partly fueled by religious tensions, societal anxieties, and economic upheaval. European belief in witchcraft gradually dwindled during and after the Age of Enlightenment.

One text that shaped the witch-hunts was the Malleus Maleficarum, a 1486 treatise that provided a framework for identifying, prosecuting, and punishing witches. During the 16th and 17th centuries, there was a wave of witch trials across Europe, resulting in tens of thousands of executions and many more prosecutions. Usually, accusations of witchcraft were made by neighbours and followed from social tensions. Accusations were most often made against women, the elderly, and marginalized individuals. Women made accusations as often as men. The common people believed that magical healers (called 'cunning folk' or 'wise people') could undo bewitchment. These magical healers were sometimes denounced as harmful witches themselves, but seem to have made up a minority of the accused. This dark period of history reflects the confluence of superstition, fear, and authority, as well as the societal tendency of scapegoating. A feminist interpretation of the witch trials is that misogyny led to the association of women and malevolent witchcraft.

The Medieval Inquisition was a series of Inquisitions (Catholic Church bodies charged with suppressing heresy) from around 1184, including the Episcopal Inquisition (1184–1230s) and later the Papal Inquisition (1230s). The Medieval Inquisition was established in response to movements considered apostate or heretical to Roman Catholicism, in particular Catharism and Waldensians in Southern France and Northern Italy. These were the first of many inquisitions that would follow.

The Cathars were first noted in the 1140s in Southern France, and the Waldensians around 1170 in Northern Italy. Before this point, individual heretics such as Peter of Bruis had often challenged the Church. However, the Cathars were the first mass organization in the second millennium that posed a serious threat to the authority of the Church. This article covers only these early inquisitions, not the Roman Inquisition of the 16th century onwards, or the somewhat different phenomenon of the Spanish Inquisition of the late 15th century, which was under the control of the Spanish monarchy using local clergy. The Portuguese Inquisition of the 16th century and various colonial branches followed the same pattern.

An inquisition was a Catholic judicial procedure in which ecclesiastical judges could initiate, investigate and try cases in their jurisdiction. Popularly the Inquisition became the name for various medieval and reformation-era state-organized tribunals whose aim was to combat heresy, apostasy, blasphemy, witchcraft, and customs considered to be deviant, using this judicial procedure. Violence, isolation, certain torture or the threat of its application, have been used by inquisitions to extract confessions and denunciations. Inquisitions with the aim of combatting religious sedition (e.g. apostasy or heresy) had their start in the 12th-century Kingdom of France, particularly among the Cathars and the Waldensians. The inquisitorial courts from this time until the mid-15th century are together known as the Medieval Inquisition. Other banned groups investigated by medieval inquisitions, which primarily took place in France and Italy, include the Spiritual Franciscans, the Hussites, and the Beguines. Beginning in the 1250s, inquisitors were generally chosen from members of the Dominican Order, replacing the earlier practice of using local clergy as judges.

Inquisitions also expanded to other European countries, resulting in the Spanish Inquisition and the Portuguese Inquisition. The Spanish and Portuguese inquisitions often focused on the New Christians or Conversos (former Jews who converted to Christianity to avoid antisemitic regulations and persecution), the Marranos (people who were forced to abandon Judaism against their will by violence and threats of expulsion), and on the Moriscos (Muslims who had been forced to convert to Catholicism), as a result of suspicions that they had secretly maintained or reverted to their previous religions, as well as the fear of possible rebellions, as had occurred in previous times (such as the First and Second Morisco Rebellions). Spain and Portugal also operated inquisitorial courts not only in Europe, but also throughout their empires: the Goa Inquisition, the Peruvian Inquisition, and the Mexican Inquisition, among others. Inquisitions conducted in the Papal States were known as the Roman Inquisition.

Religious disaffiliation is the act of leaving a faith, or a religious group or community. It is in many respects the reverse of religious conversion. Several other terms are used for this process, though each of these terms may have slightly different meanings and connotations.

Researchers employ a variety of often pejorative terms to describe disaffiliation, including defection, apostasy and disengagement. This is in contrast to excommunication, which is disaffiliation from a religious organization imposed punitively on a member, rather than willfully undertaken by the member.

K-P-R is a Semitic root, in Arabic and Hebrew rendered as K-F-R (Arabic: ك-ف-ر; Hebrew: כ-פ-ר).The basic meaning of the root is "to cover", but it is used in the sense "to conceal" and hence "to deny", and its notability derives from its use for religious heresy or apostasy (as it were describing the "concealment" of religious truth) in both Islam and Judaism.