One world religion

One world religion refers to the idea of the establishment of a single global religion, formed by a merger of all existing religions.

Some see this prospect positively, seeing all religions as ultimately one, and envisioning their peaceful union as they all come to realise their essential oneness. This idea is at times associated with New Age thought.

Others see this prospect negatively — many premillennialist Christians believe that the Antichrist will establish one world religion, based on Satanism and the occult, during the End Times, associated with one world government. Contrary to New Age views which see this as a peaceful development, they believe that the one world government will impose the one world religion by force, and that those who refuse to accept it will be persecuted, tortured, and/or executed. They generally see ecumenical policy as a step toward this world religion.

Paranoid conspiracy theorists predict the emergence of a one world religion or unified global church as a sinister plot engineered by a masonic New World Order aided by the United Nations. Fundamentalist extremists such as Jack Chick blame it all on the Catholic Church.

Those with a basic grasp of global politics or theology view the establishment of one world religion as extremely unlikely. They see the religions of the world as too fundamentally different for a peaceful union between them to ever be attainable (Hindus say there are many gods, Abrahamics say there is only one God, pantheists say that the universe is God, Buddhists don't believe in any gods, etc), and doubt that there would ever exist any government with sufficient power to forcibly unite all the world's major religions into one.

Ironically, in fundamentalist circles (especially Christian ones), the desire for religious supremacy actually reflects this very concept. Of course, what these fundamentalists have in mind is less a merger of all religions and more the utter eradication of all religions except for theirs.

In popular culture
In some works, such as the role-playing game Anima: Beyond Fantasy, there's a global religion ((a sort of) Christianity, complete with a worldwide government). However, it's much easier, as happens in that game, when there's a very powerful and technologically advanced organization moving the strings behind the scenes (having created said religion, made the world much smaller than it actually is, having a sort of Mind control devices, etc; when things get messed up, no more global government and religious schisms begin to pop up), and of course when one deals with a fictional setting with magic, psionic powers, and all that jazz.

In Left Behind, there is the Enigma Babylon One World Faith, which essentially is based on positive psychology and liberal ecumenism.