Christianity in Algeria

Christianity came to North Africa in the Roman era. According to historian Theodor Mommsen what is now Mediterranean Algeria was fully Christian by the fifth century. A notable Berber Christian of Algeria was Saint Augustine (and his mother Saint Monica), important saints of Roman Catholicism. Christianity's influence declined during the chaotic period of the Vandal invasions but was strengthened in the succeeding Byzantine period. After the Arab invasions of the 7th century, Christianity began to gradually disappear. 
Currently, North Africa is primarily Muslim: Islam is the state religion of Algeria, Libya, Morocco and Tunisia. While the practice and expression of other faiths is guaranteed by law, the same legal framework tends to restrict minority religions from actively seeking conversion to their religion, or even building or repairing churches. Converts to Christianity may be investigated and searched by the authorities as well as punished. There is some evidence that there has been an increase in conversions to Christianity among North African Muslims in recent years, even though in many cases the government will not change the religion from Islam on any citizens' identity cards. Despite this, the total number of Christians remains very low relative to the populations of these countries. In 2009, the percentage of Christians in Algeria was less than 2%. In this same survey, the United Nations counted 100,000 Roman Catholics and 45,000 Protestants in the country. Although Christians are a religious minority in Algeria, churches built during French rule can still be found. 
Conversions to Christianity have been most common in Kabylie, especially in the wilaya of Tizi-Ouzou. In Tizi-Ouzou, the proportion of Christians has been estimated to be between 1% and 5%. Christians have at times been subjected to religiously motivated attacks. A 2015 study, estimated 380,000 Muslims converted to Christianity in Algeria. In 1996, Pierre Claverie, bishop of Oran, was assassinated by terrorists. This murder occurred soon after that of seven monks of the Trappistes of Tibérine, and of six nuns. This terrorist act was part of a general trend of violence during the Algerian Civil War in the 1990s, commonly known as the Black Decade. During this time, between 100,000 and 200,000 Algerians lost their lives.
Protestantism.
Protestants number approximately 45,000 in Algeria, according to more conservative estimates. A 2015 study, however, estimated 380,000 Muslims converted to Christianity in Algeria. This small population generally practices its faith without government interference but incidences of persecution were more frequently recorded of late. Missionary groups are permitted to conduct humanitarian activities without government interference as long as they are discreet and do not proselytize openly. Since 2006 missionary outreach among Muslims can be punished with up to five years of prison. The Protestant Church of Algeria is a united church formed by the Methodist Church and Reformed Church with about 10,000 members. The Protestant Church of Algeria is one of only two officially recognized Christian organizations in the country. According to the ICC, most Christians meet in homes, to protect themselves. The country's Minister of Religious Affairs has called the evangelical churches "dangerous."
Protestant denominations in Algeria include:
History of Christianity in Algeria.
Indigenous Christianity after the Arab conquest.
The conventional historical view is that the conquest of North Africa by the Islamic Umayyad Caliphate between AD 647 and 709 effectively ended Christianity in North Africa for several centuries. The prevailing view is that the Church lacked the backbone of a monastic tradition and was still suffering from the aftermath of heresies including the Donatist heresy that contributed to the earlier obliteration of the Church in the present day Tamazgha. 
However, new scholarship has appeared that disputes this. There are reports that the Christian faith persisted in the region from Tripolitania (present-day western Libya) to present-day Morocco for several centuries after the completion of the Arab conquest by 700 AD. A Christian community is recorded in 1114 in Qal'a in central Algeria. There is also evidence of religious pilgrimages after 850 AD to tombs of Christian saints outside of the city of Carthage, and evidence of religious contacts with Christians of Muslim Spain. In addition, calendar reforms adopted in Europe at this time were disseminated amongst the indigenous Christians of Tunis, which would have not been possible had there been an absence of contact with Rome.
Local Christianity came under pressure when the Muslim fundamentalist regimes of the Almohads and Almoravids came into power, and the record shows demands that local Christians of Tunis convert to Islam. There are reports of Christian inhabitants and a bishop in the city of Kairouan around 1150 AD - a significant report, since this city was founded by Arab Muslims around 680 AD as their administrative center after their conquest. The indigenous Christian population in M'zab persisted until the 11th century. A letter in Catholic Church archives from the 14th century shows that there were four bishoprics in North Africa, admittedly a sharp decline from the over four hundred bishoprics in existence at the time of the Arab conquest. Berber Christians continued to live in Tunis and Nefzaoua in the south of Tunisia up until the first quarter of the 15th century.
Reintroduction of Christianity during French Colonialism.
The Roman Catholic Church was reintroduced in Algeria after the French conquest, when the diocese of Algiers was established in 1838. As of the last census in Algeria, taken on 1 June 1960, there were 1,050,000 non-Muslim civilians (mostly Catholic) in Algeria (10 percent of the total population including 130,000 Algerian Jews). 
Under French rule, the Catholic population of Algeria peaked at over one million. The country was divided into four dioceses, including one archdiocese:
During French rule, Christianity was used as a tool of assimilation. French colonizers attempted to convert the Muslim population to Christianity as a form of modernization. Laws were put in place to establish Algerians’ rights as citizens based on religion. The Crémieux Decree of 1870 denied Muslim Algerians full citizenship status while granting local Christian and Algerian Jewish inhabitants full citizenship. Very few Algerians converted because of this law. The religion-based citizenship divides established during the French colonial rule sparked animosity between groups that would impact the stance of minority religions in Algeria for years post-colonial rule.
Christianity after Independence.
After Algeria became independent in 1962, about 800,000 "Pieds-Noirs" of French nationality were evacuated to European France. The majority of those who evacuated were Christian or Jewish. Approximately 200,000 Algerian inhabitants of French nationality chose to remain in Algeria. The number of people with French nationality has continued to decrease over the decades. There were approximately 100,000 in 1965 and about 50,000 by the end of the 1960s.
Proselytization of the Muslim population was at first strictly prohibited; later the prohibition was less vigorously enforced, but few conversions took place. The several Roman Catholic missions established in Algeria mostly worked on charitable and relief work, the establishment of schools, workshops, and infirmaries, and the training of staff for the new establishments. Some of the missionaries of these organizations remained in the country after independence, working among the poorer segments of the population. In the early 1980s, the Roman Catholic population numbered about 45,000, most of whom were foreigners or Algerians who had married French or Italians.
Since independence, there has been a rise of Islamic fundamentalism. The 1996 murder of Pierre Claverie, bishop of Oran was an act of violence by Islamic extremist terrorists against the Christian community.
References.
Translated from : Introduction and Christianisme en Algérie sections