Akbar was ruling a land with both Muslims and Hindus. Their religions had many differences, but Akbar wished to play these differences down so that the two peoples could exist in harmony. Therefore, he introduced 'Din i Ilahi', a faith created in order to form a bridge between Islam and Hinduism.
I'm not completely sure, but the religion included practices like bowing to Akbar, prohibition of slaughtering cows on certain days, ban on the ritual of Suttee, and the belief that Akbar was the vice regent of God. The last one I am not sure about.
Most of the Muslim ulema criticized this, because there were definite differences between the two faiths. The religion never had many followers, and in Akbar's last days, even he reverted to Orthodox Islam. After Akbar's death, the faith died out completely.