The oldest known organized religion in the world is Hinduism, which traces its origins back over 4,000 years to ancient civilizations in the Indus Valley and later in the Indian subcontinent. It is often considered not just a religion but a way of life, with a complex system of beliefs, rituals, and practices centered around concepts such as dharma (duty), karma (action and consequence), and moksha (liberation from the cycle of rebirth).

The oldest known organized religion in the world is Hinduism, which traces its origins back over 4,000 years to ancient civilizations in the Indus Valley and later in the Indian subcontinent. It is often considered not just a religion but a way of life, with a complex system of beliefs, rituals, and practices centered around concepts such as dharma (duty), karma (action and consequence), and moksha (liberation from the cycle of rebirth).

As for the most popular religion today, Christianity is the largest religion globally, with over 2.3 billion followers. It is followed by Islam, with about 1.9 billion adherents. Hinduism, with about 1.2 billion followers, remains one of the world's major religions, primarily practiced in India and Nepal but with a significant global presence as well.

Thus, while Hinduism is among the oldest, Christianity is currently the most widely practiced religion worldwide.