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. 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. 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.