Major religions have been distinguished from minor religions using a variety of methods of lumping, though any such division naturally reflects a particular bias, since adherents of many religions are likely to consider their own faith "major".
Another inherent difficulty in covering the subject “world religions” is the problem of what to consider as a distinct religion versus what to consider as minor variants within the same basic religion. For example, Catholicism, Eastern Orthodoxy, Protestantism and Restorationism are commonly considered variants of Christianity, although they all have been at odds historically and doctrinally; the same is true between Sunni and Shi'a Islam.
The major religions of the world can be considered to fall into logical groupings:
Abrahamic religions are by far the largest group, and these consist primarily of the Christianity, Islam, Judaism (also referred to as Religions of the Book), and Bahá'í Faith religions. All the religions in this group are related by their belief in Abraham and their strict belief in a monotheistic divine entity. Today, around 3.4 billion people are followers of Abrahamic religions and are spread widely around the world apart from the regions around South-East Asia and China. Zoroastrianism and its derived faiths are closely linked to the Abrahamic religions and are considered by some to be a major influence on Abrahamic thought.
Major religions have also been identified based on their perceived importance, whether theological or temporal. This sorting has generally been the preserve of Western, Christian scholars, so lists of classic major religions portray this bias. Early Christian scholars, the earliest known classifiers of major religions, recognized only three religions: Christianity, Judaism, and Paganism (which they considered to encompass every other religion). Views evolved during the Enlightenment, however, and, by the nineteenth century, Western scholars considered the five major religions to be Judaism, Christianity, Islam, Hinduism, and Buddhism.
As the exposure of Westerners to other religions increased, six other religions were added to the original five: Confucianism, Taoism, Jainism, Shinto, Sikhism, and Zoroastrianism. Later, the Bahá'í Faith was added to this list, resulting in twelve classic religions: