Zoroastrianism was one of the first religions to postulate an omnipotent and invisible god. Their scripture is the Zend-Avesta, which describes the continual conflict between the forces of good and evil. Their god is Ahura Mazda, the god of light, who is symbolised by fire. Parisis worship in fire temples and wear a sadra, or sacred shirt, and a kasti, or sacred thread. Children first wear these sacred items in a ceremony known as Navjote.
Flames burn eternally in their fire temples and are worshipped as a symbol of their god.
Because Parsis believe in the purity of elements, they will not cremate or bury their dead since this might pollute the fire, earth, air or water. Instead, they leave the bodies in 'Towers of Silence' where they are soon cleaned off by vultures. Incidentally, the ceremony of the 'Sudreh Kusti' is similar to that of sacred-thread wearing ceremony among the Brahmins. Manashni, Gavashni and Kunashni' is the message of Prophet Asho Jarthustra. It means that communion with Ahurmazda can be had only through purity and nobility of thought, speech and action.