Western religion refers to the Judeo-Christian faith tradition that is widespread in the Western world, in particular in the domestic context. This tradition has been closely related to modern secularism's development, but it didn't develop in a vacuum. It evolved within a specific ideological and cultural context. Although some people practice traditional Western religions, others have left the faith. Some are more hostile to this tradition.
Christianity
You are wrong to think Christianity is a west-only religion. This religion is a worldwide phenomenon. It is practiced in over 190 countries. It is a powerful force and aims to unify people from all regions. Its doctrines are held dear to its followers.
Despite Christianity being the dominant religion in Western World, it has been changing for quite some time. Christianity has a stronger presence elsewhere than it does in Western countries. This is just one part of the story. Many Eastern groups have clung to the excuse that Christianity is a western religion.
Marxism
Although some Christians are unsure whether Marxism should be considered a religion, or a political ideology, the majority of Christians do not believe so. Both are religions. The Christian faith asserts that God created us and that we are an individual, not a collection. Marxism rejects this view and asserts that man is socially and culturally interdependent.
Marx was not an atheist but he was very materialistic and had strong views towards science. He also greatly admired scientific inquiry. This is how his atheism was expressed in his opposition towards religious belief.
Progressivism
Progressivism is a western religious idea that seeks to improve the world by eliminating old beliefs and replacing them. Instead of relying on divine guidance for guidance, this method of religion focuses on the attempt to correct the mistakes of the past and to reshape our present. Progressivism rejects any notion of a soul, and seeks to replace this idea with an artificial, naturalistic reality. Progressivism, while attempting to destroy old beliefs and replace them by new ones, also offers hope for society.
Progressives believe that humankind is on the "right" side of history, and that human beings can discern History's goals. They believe progress is inevitable because of the changing of human values. This eventually leads to an idealized history that does not include religion and classes. This view, unfortunately, is not supported empirically and is based in an extravagantly ideological and religious outlook.
Eastern Orthodox Church
Some Westerners believe that Eastern Orthodox Christianity is a Western religion. This belief is unfounded. But, there has been a disturbing incident. One priest of the Orthodox Church was temporarily suspended for wearing a cassock during a rally supporting Unite the Right in Washington, D.C. Other clergy have also voiced their political opinions via social media and personal blogs.
Orthodox Christianity places the Holy Trinity at its core. It is a concept that transcends traditional Western religions. Orthodox Christians believe Christ suffered the death of a human being, was cast into Hell, then rose again to save sinners still trapped in Hell. In this way, he cleansed mankind from its guilt and extricated them from Hell.