According to Adherents.com, that distinction still belongs to Christianity. The following figures are given for the top ten religions worldwide.
# Christianity: 2.1 billion
# Islam: 1.5 billion
# Secular/Nonreligious/Agnostic/Atheist: 1.1 billion
# Hinduism: 900 million
# Chinese traditional religion: 394 million
# Buddhism: 376 million
# primal-indigenous: 300 million
# African Traditional & Diasporic: 100 million
# Sikhism: 23 million
# Juche: 19 million
Islam
Islam is a religon, so its the second-biggest religon in the world and the fastest-growing.
I hope its free thinkers!
Islam
Islam Islam
Islam is the religon of Muslims so people who follow the religon of Islam are Muslims.
Christianity and Islam are the most common religions.
The countries of the world that Islam is a majority religon in or influenced by Islam. Like Indonesia has the most Muslim population. The Middle East, some part of Europe, etc
One billion people and still growing... second largest and fastest growing religon
Islam Islam
Islam
Islam