What religion dominates in the west, and what religion dominates in the east?

West is dominated by Christianity and East is dominated by the Islam and Buddhism.

Explanation:

Western countries are settled colonies by the European countries which is the origin of Christianity and birth place of Jesus. Eastern country are dominated by Buddhism and Islam. Middle countries were majorly Islam and some countries are following the Hinduism. India is the birth place of Buddhism which is the birth place of Gautama Buddha in the 6th century, it spread along the major Asian countries. Prophet Mohammad is the founder of the Islam religion which spreaded by the Islam traders through the Indian ocean route.