A recently released report from the Pew Research Center found that, from 2010 to 2020, Islam was the fastest-growing religion in the world, increasing by 347 million adherents over the decade.

While the report noted that Christianity remains the largest religion in the world, its share has decreased by 1.8% to a total of 2.3 billion people, or roughly 29% of the world’s population. Islam is also the second-largest religion, with two billion people representing 25.6% of the world’s population.

Meanwhile, the second fastest-growing group is the non-religiously affiliated, also known as the “nones.” The nones are “the main driver of the decline in the Christian share of the global population,” according to the report. “Religious disaffiliation — primarily of people leaving Christianity — also is the main driver of the growth of religiously unaffiliated populations.”

In other words, while Islam is rapidly growing, Christianity is slowly declining.

Interestingly, the most significant driver behind both the growth of Islam and the decline of Christianity has everything to do with birth rates. Simply put, Muslims are having more children while Christians are having fewer.

As Muslim writer Sayed Mahdid Al-Modarresi explains, Islam’s “religious scriptures are clear as daylight that Islam wants us to have as many children as possible.”

Indeed, as Conrad Hackett, a senior demographer at Pew, notes, “Very little of the change in Muslim population size is a result of people becoming Muslim as adults or leaving Islam as adults.”

Regarding Christians, the issue appears to be twofold. First, the birthrate among Christians has declined; however, the most significant driver of decline has been religious disaffiliation. This has been especially true in Europe and North America.

The report observes, “Religious disaffiliation is the main driver of the decline in the Christian share of the global population. Religious disaffiliation — primarily of people leaving Christianity — also is the main driver of the growth of religiously unaffiliated populations.”

As the report notes, the growth of the nones is largely due to people disaffiliating from Christianity. “Christians have experienced the biggest net losses from switching (3.1 have left for every 1.0 who has joined),” the report states. “Most former Christians no longer identify with any religion, but some now identify with a different religion.”

The continent with the largest number of Christians is now Africa, with over 30% of the world’s Christians living in sub-Saharan Africa, while Europe contains a shrinking population now numbering just 22.3% of the world’s Christians.

Given this data, while the majority of countries remain Christian-majority, in some 120 countries, the religious disaffiliation is changing them. In the United Kingdom, Austria, and France, the percentages of the population that are Christian have dropped to a plurality at 49%, 47%, and 46%, respectively.

The report estimates that if current trends continue, America will no longer be a majority Christian nation by 2045.

For Christians, this should be sobering news. And it should serve as a wakeup call for Christians to do what Jesus called us to do — namely, “Go therefore and make disciples of all nations, baptizing them in[a] the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.” (Matthew 28:19-20)