Original sentence: Chinese interest in alchemy and the elixir of life declined in proportion to the rise of Buddhism, which claimed to have alternate routes to immortality.However, the elixir of immortality was not of great interest in India because Hinduism, the primary Indian religion, claimed to have alternate routes to immortality.No such potion has ever been discovered though alchemists in ancient China, India, and the West spent a great deal of time and effort on it
Edited sentence: Chinese interest in alchemy and the elixir of life declined in proportion to the rise in  Buddhism, with its alternative routes to immortality.However, the elixir of immortality was not of great interest in India because Hinduism, the primary Indian religion (like Christianity) provided other avenues to immortality.Naturally, no such potion has ever been discovered though alchemists in ancient China, India, and the West spent a great deal of time and effort on it