Indian culture is shaped by various eras of history, customs, traditions, and ideas, influenced by both invaders and immigrants. Many cultural customs, languages, and monuments exemplify this intermingling over the centuries. Historically, Indian culture has extended far beyond the borders of the modern state of India; this historical cultural region is called "Greater India," and encompasses territories from Central Asia to Southeast Asia.
Modern India exhibits cultural and religious diversity, even within the country's regions. The southern, northern, and northeastern parts have their own distinctive characteristics, and virtually all states have carved out their own cultural niche. Despite this unique cultural diversity, the entire country is united as a civilization due to its shared history, thereby preserving its national identity.
India is the birthplace of religious systems such as Hinduism, Jainism, Buddhism, and Sikhism, which have exerted a significant influence not only on India but also on the entire world. Following the Islamic invasion and subsequent foreign rule from the 10th century onward, Indian culture was heavily influenced by Persian, Arabic, and Turkic cultures. In turn, India's diverse religions and traditions influenced Southeast Asia and other parts of the world. Mark Twain wrote:
"India is the cradle of the human race, the cradle of human speech, the mother of history, the grandmother of legend, and the great-grandmother of tradition. Our most valuable and most important records of human history are preserved in India alone!"
Indian religions, also known as Dharmic, are major religions alongside the Abrahamic ones. Today, Hinduism and Buddhism are the third and fourth largest religions in the world, with followers exceeding 2 billion and possibly reaching 2.5 or 2.6 billion. India is one of the most religiously diverse countries in the world, with some deeply religious societies and cultures. Religion continues to play a central and defining role in the lives of many of its inhabitants.
According to the 2001 census, 80% of the population is Hindu, and about 13% is Muslim. India is also home to over 23 million Christians, over 19 million Sikhs, approximately 8 million Buddhists, and about 4 million Jains. Buddhism, Jainism, and Sikhism have influenced not only India but the entire world. Christianity, Zoroastrianism, Judaism, and the Bahá'í faith have also had an impact, but their numbers are small. Atheism and agnosticism have also left a significant mark on Indian culture, along with those who consider themselves tolerant of others.
In India, there are important historical debates regarding the concept, relevance, existence, and non-existence of God.