Final answer:
Christianity is the religion with the most followers worldwide, followed by Islam, Hinduism, and then Buddhism.
Step-by-step explanation:
The religion with the most followers worldwide is Christianity. Christianity has about 2.2 billion adherents, making it the largest religion globally at this time. Islam is the second-largest religion, with approximately 1.5 billion followers. While it is the fastest growing and is expected to have many adherents by 2020, as of the latest data, it does not surpass Christianity in number. Buddhism, with a significant presence in countries like China and others across Asia, comes in fourth place after Hinduism, which has around 900 million followers. Judaism, like Buddhism and Islam, is a monotheistic religion but has fewer followers compared to these larger religions.