Religions through time: The rise and shift of global faiths

In the early centuries of recorded history, Hinduism emerged as the dominant global religion. Rooted in the Indian subcontinent, it held the largest following for much of ancient and medieval history due to population growth and cultural consolidation in South Asia.

Subsequently, Christianity’s explosive rise from the 1st century CE became evident. Spurred by the Roman Empire’s adoption and European colonisation over centuries, Christianity surpassed all other religions by the 16th–17th century and has maintained that lead into the modern day.

In parallel, Islam rose swiftly after the 7th century CE, spreading from the Arabian Peninsula into the Middle East, North Africa, Central Asia, and parts of Europe and Southeast Asia. Today, it stands as the second-largest religion globally, and its growth trajectory remains steep due to high birth rates in Muslim-majority countries.

The fade of ancient faiths

Ancient polytheistic religions—such as those of the Greeks, Romans, Egyptians, and Norse—which once dominated their regions, saw a decline following the spread of monotheistic faiths.

Buddhism, although never the largest in terms of global population, however, retains a significant and steady presence, particularly in East and Southeast Asia, thanks to early missionary efforts and cultural integration.

Modern shifts: The rise of secularism

By the 20th and 21st centuries, a new category began to climb: the religiously unaffiliated. This includes atheists, agnostics, and those who identify as "spiritual but not religious." Driven largely by secularisation in Europe, North America, and parts of East Asia, this group has grown rapidly—making it one of the largest belief segments today.

In a nutshell, Christianity remains the largest religion, with over 2.3 billion followers. Islam follows closely with 1.9 billion, projected to surpass Christianity by the end of the 21st century. The "unaffiliated" now make up more than 1 billion people, a number that continues to grow.