Short answers, pulled from the story.
Din-i Ilahi was a syncretic theology founded by Mughal emperor Akbar in 1582. The name translates as "God's Religion" or "Divine Religion", though during Akbar's lifetime it was called Tawhid-i-Ilahi, meaning "Oneness of the Divine". It drew from Islam, other Abrahamic religions, Dharmic traditions, and Zoroastrianism.
Din-i Ilahi never had more than 19 identified followers. Named disciples included Abu'l-Fazl ibn Mubarak, Birbal, Prince Murad, Shaikh Mubarak, Shaikh Faizi, and Qasim Khan, among others. The religion lasted just over 20 years before it was suppressed.
Akbar built the Ibādat Khāna, or House of Worship, at Fatehpur Sikri in 1575. He invited theologians, poets, scholars, and philosophers from all faiths, including Christians, Hindus, Jains, and Zoroastrians, to debate religious and philosophical questions there.
Muslim scholars of the period declared Din-i Ilahi to be blasphemy and condemned Akbar as an apostate. Among the most prominent critics were the qadi of the Bengal Subah and the theologian Shaykh Ahmad Sirhindi, who publicly decried Akbar's conversion to the new faith.
Din-i Ilahi promoted the unity of God, vegetarianism, ahimsa (nonviolence), abstinence from the company of fishers and hunters, and the use of greetings such as Allah-u-Akbar. It incorporated Sufi spirituality, Zoroastrian light-fire ritual, Hindu yoga, and the Buddhist practice of shaving the crown of the head. The religion had no sacred scriptures and no priestly hierarchy.
Din-i Ilahi was suppressed by force after Akbar's death. A 17th-century attempt to revive it by Dara Shikoh, Shah Jahan's eldest son, was ended when his brother Aurangzeb executed him on grounds of apostasy. Aurangzeb then reimposed the jizya, compiled the Fatawa-e-Alamgiri, and established Islamic law across the Indian subcontinent, extinguishing any prospect of revival.