Given the inherent diversity in international political thought, the term Christian left can have different meanings and applications in different countries. While there is much overlap, the Christian left is distinct from liberal Christianity, meaning not all Christian leftists are liberal Christians and vice versa. Christian anarchism, Christian communism and Christian socialism are subsects of the socialist Christian left, although it also includes more moderate Christian left-liberal and social-democratic viewpoints.
As with any section within the left and right wings of a political spectrum, a label such as Christian left represents an approximation, including within it groups and persons holding many diverse viewpoints. The term left-wing might encompass a number of values, some of which may or may not be held by different Christian movements and individuals.
As the unofficial title of a loose association of believers, it does provide a clear distinction from the more commonly known "Christian right" or "religious right" and from its key leaders and political views.
The most common religious viewpoint that might be described as "left-wing" is social justice, or care for impoverished and oppressed groups. Supporters of this trend might encourage universal health care, welfare provisions, subsidized education, foreign aid, and affirmative action for improving the conditions of the disadvantaged. With values stemming from egalitarianism, adherents of the Christian left consider it part of their religious duty to take actions on behalf of the oppressed. Matthew 25:31-46, among other verses, is often cited to support this view. As nearly all major religions contain some kind of requirement to help others, adherents of various religions have cited social justice as a movement in line with their faith.
The term social justice was coined in the 1840s by Luigi Taparelli, an Italian Catholic scholar of the Society of Jesus, who was inspired by the writings of Thomas Aquinas. The Christian left holds that social justice, renunciation of power, humility, forgiveness, and private observation of prayer (as in ) as opposed to publicly mandated prayer, are mandated by the Gospel. The Bible contains accounts of Jesus repeatedly advocating for the poor and outcast over the wealthy, powerful, and religious. The Christian left maintains that such a stance is relevant and important. Adhering to the standard of "turning the other cheek", which they believe supersedes the Old Testament law of "an eye for an eye", the Christian left sometimes hearkens towards pacifism in opposition to policies advancing militarism.
Some among the Christian left, as well as some non-religious socialists, find support for anarchism, communism and socialism in the Gospels (for example Mikhail Gorbachev citing Jesus as "the first socialist"). The Christian left is a broad category that includes Christian socialism, as well as Christians who would not identify themselves as socialists.
For much of the early history of anti-establishment leftist movements such as socialism and communism (which was highly anti-clerical in the 19th century), some established churches were led by clergy who saw revolution as a threat to their status and power. The church was sometimes seen as part of the establishment. Revolutions in America, France, Russia and (much later) Spain were in part directed against the established churches (or rather their leading clergy) and instituted a separation of church and state.
In the 19th century, some writers and activists developed the school of thought of Christian socialism, which infused socialist principles into Christian theology and praxis.
Early socialist thinkers such as Robert Owen, Henri de Saint-Simon based their theories of socialism upon Christian principles. Karl Marx and Friedrich Engels reacted against these theories by formulating a secular theory of socialism in The Communist Manifesto.
Starting in the late 19th century and early 20th century, some began to take on the view that genuine Christianity had much in common with a leftist perspective. From St. Augustine of Hippo's City of God through St. Thomas More's Utopia, major Christian writers had expounded upon views that socialists found agreeable. Of major interest was the extremely strong thread of egalitarianism in the New Testament. Other common leftist concerns such as pacifism, social justice, racial equality, human rights, and the rejection of excessive wealth are also expressed strongly in the Bible. In the late 19th century, the Social Gospel movement arose (particularly among some Anglicans, Lutherans, Methodists and Baptists in North America and Britain,) which attempted to integrate progressive and socialist thought with Christianity to produce a faith-based social activism, promoted by movements such as Christian socialism. In the United States during this period, Episcopalians and Congregationalists generally tended to be the most liberal, both in theological interpretation and in their adherence to the Social Gospel. In Canada, a coalition of liberal Congregationalists, Methodists, and Presbyterians founded the United Church of Canada, one of the first true Christian left denominations. Later in the 20th century, liberation theology was championed by such writers as Gustavo Gutierrez and Matthew Fox.
To a significant degree, the Christian left developed out of the experiences of clergy who went to do pastoral work among the working class, often beginning without any social philosophy but simply a pastoral and evangelistic concern for workers. This was particularly true among the Methodists and Anglo-Catholics in England, Father Adolph Kolping in Germany and Joseph Cardijn in Belgium.
Some Christian groups were closely associated with the peace movements against the Vietnam War as well as the 2003 Invasion of Iraq. Religious leaders in many countries have also been on the forefront of criticizing any cuts to social welfare programs. In addition, many prominent civil rights activists (such as Martin Luther King Jr. in the United States) were religious figures.
In the United States, members of the Christian Left come from a spectrum of denominations: Peace churches, elements of the Protestant mainline churches, Catholicism, and some evangelicals. Organizations that represent various ideological trends within the Christian Left include Sojourners, founded by Jim Wallis in 1971, Bread for the World, Evangelicals for Social Action, and other faith-based advocacy groups.
In the aftermath of the 2004 election in the United States, progressive Christian leaders started to form groups of their own to combat the religious right. Such groups include the Center for Progressive Christianity (founded 1996) and the Christian Alliance for Progress.
The Christian left generally approaches homosexuality differently from some other Christian political groups. This approach can be driven by focusing on issues differently despite holding similar religious views, or by holding different religious ideas. Those in the Christian left who have similar ideas as other Christian political groups but a different focus may view Christian teachings on certain issues, such as the Bible's prohibitions against killing or criticisms of concentrations of wealth, as far more politically important than Christian teachings on social issues emphasized by the religious right, such as opposition to homosexuality. Others in the Christian left have not only a different focus on issues from other Christian political groups, but different religious ideas as well.
For example, all members of the Christian left consider discrimination and bigotry against homosexuals to be immoral, but they differ on their views towards homosexual sex. Some believe homosexual sex to be immoral but unimportant compared with issues relating to social justice, or even matters of sexual morality involving heterosexual sex. Others assert that some homosexual practices are compatible with the Christian life. Such members believe common biblical arguments used to condemn homosexuality are misinterpreted, and that biblical prohibitions of homosexual practices are actually against a specific type of homosexual sex act, i.e. pederasty, the sodomizing of young boys by older men. Thus, they hold biblical prohibitions to be irrelevant when considering modern same-sex relationships.
A related strain of thought is the (Catholic and progressive evangelical) consistent life ethic, which sees opposition to capital punishment, militarism, euthanasia, abortion and the global unequal distribution of wealth as being related. It is an idea with certain concepts shared by Abrahamic religions as well as Buddhists, Hindus, and members of other religions. The late Cardinal Joseph Bernardin of Chicago developed the idea for the consistent life ethic in 1983. Sojourners is particularly associated with this strand of thought.
Liberation theology is a theological tradition that emerged in the developing world, primarily in Latin America. Since the 1960s, Catholic thinkers have integrated left-wing thought and Catholicism, giving rise to Liberation theology. It arose at a time when Catholic thinkers who opposed the despotic leaders in Southern and Central America allied themselves with the communist opposition. However, it developed independently of and roughly simultaneously with Black theology in the U.S. and should not be confused with it. The Congregation for the Doctrine of the Faith decided that while liberation theology is partially compatible with Catholic social teaching, certain Marxist elements of it, such as the doctrine of perpetual class struggle, are against Church teachings.
A number of movements of the past had similarities to today's Christian left:
The Christian Alliance for Progress. composed of individuals from various denominations and religious viewpoints, strives to emphasize the core beliefs and values of Christianity in response to the contemporary involvement of Christian groups in the search for political influence and power.