The Pew Research Center published a study on Tuesday stating that Islam was the fastest-growing religion in the world between 2010 and 2020, reaching two billion adherents.

The research behind this new development spanned 201 countries and looked into the world’s five most popular religions: Christianity, Islam, Judaism, Buddhism and Hinduism. Followers of other faiths and atheists were also mentioned.

The study explained that while Christianity grew by 122 million people over the 10-year duration, Islam grew by 347 million people, a 20% increase since the study began.

Pew explained that demographics were the main reason behind Islam’s sharp growth, saying that Muslim women on average have 2.9 children, whereas non-Muslim women have 2.2.

It did, however, mention that Islam’s growth was not affected much by its conversion rate, saying that “about 1% of people who are raised Muslim leave the faith,” citing another study conducted between 2008 to 2024.

The recent study also pointed out that most of the world’s Muslims originate from outside the Middle East and North Africa (MENA) region, such as Indonesia, Pakistan, India and Bangladesh.

Regarding Islam in the United States specifically, conversions and immigration provide a steady increase of Muslims.

According to the US Religion Census published in 2020, over 4.5 million Muslims live in the country, comprising 1.3% of its 342 million population.

While Islam in the US boasts a high conversion rate with roughly 25% of Muslims being converts, a Pew study published in 2018 cited that 23% of Muslims raised in the country end up leaving the faith.

Despite this, Ibrahim Hooper, the Communications Director of the Council on American-Islamic Relations (CAIR), the largest Muslim advocacy group in the United States, said that Islam’s growth specifically in the US “is due to a number of factors, including conversion, a higher-than-average birth rate and immigration from Muslim-majority areas."

42% of Muslims in the US are born in the country, many of whom are “converts (many of them Black) and descendants of converts,” the 2018 study added.