The most popular religion in the world is Christianity. Estimates suggest there are currently approximately two billion practicing Christians. About half of these are Catholics, and the majority shares of other Christian faiths include Protestants and Anglicans. In total, roughly 33% of those in the world practice the Christian religion in some form.

Islam comes in as the second most popular religion in the world, with approximately one billion members. Some Islamic people claim that there are actually more practicing Muslims than practicing Christians. This depends on how one defines the word “practicing.” A person who cites his/her religion as Christianity might not, for example, attend church regularly. This to a Muslim might seem like failure to practice a religion. This to the Christian might merely seem an acceptable way to practice his or her faith.

In the United States, however, the religion of Islam is the fastest growing religion. Roughly 80% of the mosques in the US were built within the last 20 years. These mosques were not built for Islamic immigrants primarily, but for those converts born in the US. Certainly an increase in immigration of people who are Muslims has increased the number of Muslims in the US. However, immigration to the US of people of the Muslim religion has slowed since 9/11.

The third largest group of the population is considered non-religious. About one billion people consider themselves to not regularly practice any religion, or to be atheists. This is actually a diverse group, including agnostics. Atheists only represent a small portion of the one billion. Many are simply unsure what religion is the right one for them, and also may have problems with organized religion in general.

About 900 million people practice the Hindu religion. Both Confucianism (sometimes called Chinese traditional religion), and Buddhist religion are practiced by close to 400 million people each. Indigenous religions and African traditional religion are practiced by approximately 300 million and 100 million people, respectively. Numbers decline into the 10 millions for religions that follow.

The top ten are as follows:
1. Christianity
2. Islam
3. Nonreligious
4. Hindu Religion
5. Chinese Traditional Religion
6. Buddhist Religion
7. Primal or Indigenous Religion
8. African Tradition Religion
9. Sikhism
10. Juche