Atum’s name means ‘The Complete One,’ and it carried the idea of totality, an ultimate and unalterable state of perfection. He was one of the great creator gods, and possibly the oldest deity worshipped at Iunu or Heliopolis, where he was called “Lord of Heliopolis” and eventually synchretized with Re to form Re-Atum, a sun god.
The Egyptian mongoose, or ichneumon, which today is called Pharaoh’s cat or kutt Fara’un is the great destroyer of snakes and crocodile eggs, and was thought to be the incarnation of Atum. One legend says that the god was once attacked by a snake, and to defend himself and destroy it, he transformed himself into a mongoose. But he is never depicted as anything but completely human from foot to head, often seated, wering the double crowns of Upper and Lower Egypt or the royal names headcloth. Other animals sacred to Atum were the lion, bull, and lizard.
Atum was thought to be a self-created god, who made the whole of creation out of himself. He first took shape as a serpent which came into being in the primeval waters of the Nun. Egyptians believed that at the end of the world Atum would revert to his serpent form and return to the Nun, which he would then allow to once again cover the earth and so destroy it and all he had made. This was recounted in the Book of the Dead, Chapter 175, as told by Atum himself to Osiris.
The earliest written story about Atum being creator was dated about 2350 BCE. The last king of the 5th Dynasty, Unas, built a pyramid tomb at Saqqara and had inscriptions carved inside on the walls of the antechamber, burial chamber, and throughout the pyramid. In these Pyramid Texts, some of which were also found in some 6th Dynasty pyramids, are a collection of so-called “spells”, which tell the creation of the world according to the Heliopolitan or Iunu theology. Utterance 527 in the Pyramid Texts relates :
"Atum is he who once came into being, (i.e. the primeval god who evolved from the Chaos.) He copulated with himself in On (Heliopolis), He took his phallus in his grasp that he might create orgasm by means of it, and so were born the twins Shu and Tefnet." Several other texts say that the procreative act took place in the Primeval Waters altogether rather than in Heliopolis. The hand with which he used to copulate with himself was personified as the female principle, and he and "his hand" appear as a divine couple on coffins of the Herakleopolitan period.
By the end of the 5th Dynasty exclusive royal power was waning. One result of this was that the Pyramid Texts became adapted for use by “common people” who were accorded burial in a tomb. The funerary texts were now painted on the wooden coffins rather than on the walls. So the Pyramid Texts became known as the Coffin Texts and add to the creation story.
In one of these, Atum speaks about the Beginning:
"I, Atum, was still alone in the waters, in a state of inertness. I had not yet found anywhere to stand or sit, and Iunu had not yet been founded that I might be therein."
Other creation variants maintain that Atum spat Shu and Tefnut out from his mouth. Perhaps this version is the forerunner of the concept that the world was created through God’s word, as in the Memphite theology with Ptah as the creator-god.
After their birth, Shu and Tefnut became separated from their father Atum and were lost in the dark immensity of the Primeval Waters of the Nun. Atum sent his Eye to look for them, and when they were found, he named the son Shu or Life, and his daughter, as Order, Tefnut, and he lay entwined with them in the Nun, keeping them safe.
Spell 80 of the Coffin Texts relates what happened next. Atum, tired of lying inert in the nun, asked it how he could create a resting place for himself. Nun tells him, “Kiss your daughter, Order; put her to your nose; so will your heart live. Never let her leave you, let Order, who is your daughter, be with your son, Shu, who is Life.” Atum then asks Shu to support him while he holds Tefnut to his nose, meaning that he kissed her. And so, Iunu came into being as the first mound which rose out of the waters of the Nun. And Atum was able to rest upon it. According to Pyramid Text 600, Atum was this mound, called the High Hill in Iunu. The first dawn and all dawns thereafter came when Atum appeared on or as the High hill.
Other accounts of this first dawn tell of a heron, called the Benu Bird, skimming over the waters of the Nun, until it came to rest on a rock. As it did so, it opened its beak and let out a cry over the silence of the Nun. So the Benu Bird came to be known as an aspect of Atum, who created himself and brought light and life to the world.
Atum formed the head of the Great Ennead, or Nine, of Heliopolis, together with Shu, Tefnut, Geb the earth and Nut the sky, their children, and the children of those children, Osiris, Horus the Elder, Seth, Isis, and Nephthys.
Atum is called the father of the king of Egypt in several places in the Pyramid Texts. In the Afterlife, Atum embraces his son, the dead monarch, raising him up to the sky as head of the star-gods. In the temple of Amun at Karnak, reliefs show Atum with Montu, gods of north and south, conducting the king into the sacred precinct for coronation rituals.
Atum quells hostile forces in the Underworld. He overcomes the dangerous
snake Nehebu-Kau by pressing his fingernail on its spine. Before Gate 9
of the Underworld, Atum stands confronting the coiled serpent Apophis,
condemning him to be overthrown and destroyed. In the tombs of the
Valley of the Kings at Thebes, the walls depict Atum resting on his
staff supervising the punishment of the enemies of the sun, by drowning
or beheading. Atum offers protection to the deceased on his journey
through the Underworld, ensuring a safe passage past the Lake of Fire.