This article describes the duality thoughts in the ancient Egyptian religious beliefs. As the term duality refers to a way of thinking which indicate two opposes or complementary; this way of thinking might be in religion, surrounding nature, culture or philosophy. Duality was presented in the ancient Egyptian religious beliefs; gods of Upper Egypt and gods of Lower Egypt and gods of the living and gods of the dead. The thoughts of the ancient Egyptians were always towards duality through both the daily life and the afterlife; this was a result of trying to attain balance between the opposing forces. The duality idea was emphasized through some aspects: life and death, day and night, and the world above the horizon and the Netherworld below. The duality thoughts were observed from the surrounding natural sources. Religion in ancient Egypt played an important and vital role in the Egyptians' understanding of the surrounding world.