Christian socialism is a religious and political philosophy that blends Christianity and socialism, endorsing left-wing politics and socialist economics on the basis of the Bible and the teachings of Jesus. Many Christian socialists believe capitalism to be idolatrous and rooted in the sin of greed. Christian socialists identify the cause of social inequality to be the greed that they associate with capitalism. Christian socialism became a major movement in the United Kingdom beginning in the 19th century. The Christian Socialist Movement, known as Christians on the Left since 2013, is one formal group, as well as a faction of the Labour Party.

According to the Encyclopædia Britannica, socialism is a "social and economic doctrine that calls for public rather than private ownership or control of property and natural resources. According to the socialist view, individuals do not live or work isolated, but live in cooperation with one another. Furthermore, everything that people produce is in some sense a social product, and everyone who contributes to the production of a good is entitled to a share in it. Society as a whole, therefore, should own or at least control property for the benefit of all its members. ... Early Christian communities also practised the sharing of goods and labour, a simple form of socialism subsequently followed in certain forms of monasticism. Several monastic orders continue these practices today." The Hutterites believe in strict adherence to biblical principles and church discipline, and practised a form of communism. In the words of historians Max Stanton and Rod Janzen, the Hutterites "established in their communities a rigorous system of Ordnungen, which were codes of rules and regulations that governed all aspects of life and ensured a unified perspective. As an economic system, Christian communism was attractive to many of the peasants who supported social revolution in sixteenth century central Europe", such as the German Peasants' War, and Friedrich Engels came to view Anabaptists as proto-communists.

Other earlier figures viewed as Christian socialists include the 19th-century writers F. D. Maurice (The Kingdom of Christ, 1838), John Malcolm Forbes Ludlow (The Christian Socialist, 1850), Adin Ballou (Practical Christian Socialism, 1854), Thomas Hughes (Tom Brown's School Days, 1857), John Ruskin (Unto This Last, 1862), Charles Kingsley (The Water-Babies, A Fairy Tale for a Land Baby, 1863), Frederick James Furnivall (co-creator of the Oxford English Dictionary), and Francis Bellamy (a Baptist minister and the author of the Pledge of Allegiance in the United States).