Christianity in Syria (Arabic: المسيحية في سوريا) has among the oldest Christian communities on Earth, dating back to the first century AD, and has been described as a "cradle of Christianity". With its roots in the traditions of St. Peter and St. Paul the Apostle, Syria quickly became a major center of early Christianity and produced many significant theologians and church leaders. Of the 200 bishops who took part in the First Council of Nicaea in 325 AD, twenty were from Syria. Over the centuries, Syrian Christians have played a vital role in shaping Christian thought and practice, contributing to the development of various liturgical traditions, monastic movements, and theological schools. St. Paul the Apostle famously converted to Christianity on the road to Damascus, and Syria has produced seven Popes: Pope Anicetus (157–168 AD), Pope John V (685–686), Pope Sergius I (687–701),, Pope Sisinnius (708), Pope Constantine (708–715), Pope Gregory III (731–741 AD), and the first pope, St. Peter, who was from Bethsaida. Their legacy includes the establishment of some of the most ancient churches, monasteries, and pilgrimage sites, such as the 5th century remains of the Church of Saint Simeon Stylites, Our Lady of Saidnaya Monastery, and the Cathedral of Constantine and Helen.

However, in recent times, the Syrian Christian community has faced numerous challenges, including ongoing and severe persecution, displacement, and emigration. Christians in Syria made up about 10% of the pre-war Syrian population but now make up less than 2%, falling from 1.5 million in 2011 to just 300,000 in 2022 due to the impact of the Syrian Civil War. Christians in Syria have also been subjected to violence and discrimination by Islamic State fighters during their control of large areas of the country. Their churches have been converted into military headquarters, and their property confiscated. Persecution of Christians in Syria has further intensified since. In Aleppo, the country's second largest city, the proportion of Christian residents fell from 12% pre-war to 1.4% in 2023 with more than 20 churches damaged during the war. The city of Idlib has been almost entirely depopulated of its Christian population under Islamist rule. Some governments and organisations including the United States have claimed that the persecution of Christians in the Middle East and North Africa, especially in Syria and Iraq, constitute an act of genocide.

The country's largest Christian denomination is the Greek Orthodox Church of Antioch, closely followed by the Syriac Orthodox Church and the Armenian Apostolic Church. There is a small minority of Protestants in the country.

In the late Ottoman rule, a large percentage of Syrian Christians emigrated from Syria, especially after the bloody chain of events that targeted Christians in particular in 1840, the 1860 massacre, and the Assyrian genocide. According to historian Philip Hitti, approximately 90,000 Syrians arrived in the United States between 1899 and 1919 (more than 90% of them Christians). The Syrians referred include historical Syria or the Levant encompassing Syria, Lebanon, Jordan and Palestine. Syrian Christians tend to be relatively wealthy and highly educated.

According to the Catholic charity group Aid to the Church (ACN), number of Christians residing in Syria is estimated to have reduced from 2.1 million (10% of population) in 2011 to around 300,000 (less than 2%) in 2022. The decrease is due to large-scale emigration of Christians to Europe triggered by deteriorating living conditions caused by the civil war. US State Department estimates that Syrian Christians comprise 2.5-3% of the total population inside Syria, as of 2022.

The Christian population of Syria comprised 10% of the Syrian population before 2011. Estimates of the number of Christians in Syria in 2022 range from less than 2% to around 2.5% of the total Syrian population.

Most Syrians are members of either the Greek Orthodox Church of Antioch (700,000), or the Syriac Orthodox Church. The vast majority of Catholics belong to the Melkite Greek Catholic Church. Other Eastern Catholic churches include the Maronite Church, Syriac Catholic Church, Armenian Catholic Church, Chaldean Catholic Church; there is also a small number of Latin Church Catholics. The rest belong to the Eastern communions, which have existed in Syria since the earliest days of Christianity when all Christians were part of the One, Holy, Catholic and Apostolic Church. The main Eastern groups are:

Even though each group forms a separate community, Christians nevertheless cooperate increasingly. Roman Rite, Western Latin Church Catholicism and Protestantism were introduced by missionaries but only a small number of Syrians are members of Western rites.