Actually Ra is a New kingdom theology. and was not present in the begining of the culture.
Atum is one of the most important and frequently mentioned deities from earliest times in Egyptian mythology, as evidenced by his prominence in the Pyramid Texts, where he is portrayed as both a creator and father to the kings.
He is usually depicted as a man wearing either the royal head-cloth or the dual white and red crown of Upper Egypt, and Lower Egypt, reinforcing his connection with kingship. The council of Atum with the nine members: Osiris, Nut, Geb, Shu, Atum, Tefnut, Nephthys, Isis and Aset. This group formed the solar cult of Heliopolis, Thebes, and Abydos.
During the Old Kingdom the Egyptians believed that Atum lifted the dead Pharaoh's soul from the tomb to the starry heavens.By the time of the New Kingdom, the Atum myth had merged in the Egyptian pantheon with that of Ra.
Ra is most commonly pronounced 'rah'. in the beginning the two were mixed to form one god Amun -RA. A deity in Egyptian mythology who in the form of Amun-Ra became the focus of the most complex system of theology in Ancient Egypt.
Amun represented the essential and hidden, whilst in Ra he represented revealed divinity. Amun was self created, without mother and father, and during the New Kingdom he became the greatest expression of transcendental deity in Egyptian theology. He was not considered to be immanent within creation nor was creation seen as as an extension of himself. Amun-Ra, As his cult arose in the Egyptian pantheon, Ra often replaced Atum as the true father of the deities of the Ennead, and as result became the creator of the world.
It appears almost certain, rather, that the Great Ennead;which are the nine deities of Atum, Geb, Isis, Nut, Osiris, Nephthys, Seth, Shu, and Tefnut; first appeared prior to the rise of Ra's cult in the sixth dynasty, and that after introduction of the new pesedjet the cult of Ra soon saw a great surgence until the worship of Horus gained prominence. Afterward worship focused on the syncretistic solar deity Ra-harakhty (Ra, who is Horus of the Two Horizons). During the Amarna Period of the eighteenth dynasty, Akhenaten introduced worship of another solar deity Aten. The deified solar disc represented his preferred regional deity as he attempted to lessen the influence of the temple of Atum.
Another belief held to Atum is that During the Old Kingdom the Egyptians believed that the mother goddess and Atum were the parents of Shu and Tefnut, the first deities. referred to as Iusa'aset (also spelt Iusas, and in Greek as Isis), meaning the great one who comes forth. In this role she often was described as his wife. Consequently As the wife of Atum, Iusa'aset was seen as the mother of the gods. Her strength, hardiness, medical properties, led the acacia tree to be considered the tree of life, and thus the oldest, which was situated close to, and north of, Heliopolis, was said to be the birthplace of the deities. Thus, as the mother of the deities, Iusa'aset was said to own this tree.
Although her origins are unclear, Iusa'aset seems to be attested quite early in the Egyptian pantheon, being associated with creation and the creation of the deities. She remains as a primary deity in the pantheon throughout all eras of the culture, even through the Persian, Hyksos, Greek, and Roman occupations, and regardless of changes in the specific myths.
At these later times Iusa'aset sometimes is described as the eye of Ra, after the myth of Ra overtook that of Atum. This implies that her cult was very strong, since she survived as a deity associated with the new deity replacing the one with whom she had been paired during the New Kingdom pantheon. An association with the Greek, and Roman occupations Isis can be found later as the Greek pronunciation of her name still being known today as Isis mother of the gods, my have lead to Roman version of Mary mother of god. both Isis and Mary are depicted as holding a single infant god.
