The moon has always played an important role in Egyptian religion, even through modern times, with it's symbolisms related to the Islamic faith. During ancient times, it was never as important to the Egyptians as the sun, though the moon was considered by them to be the nightly replacement of the sun. Within all of the known creation accounts, the Sun is always paramount. However, in the relationship between the Moon and the stars, the lunar god can be designated as "ruler of the stars".

However, unlike the solar Aten, it is uncertain that the disk of the moon was itself ever worshipped as a deity during the history of ancient Egypt. Rather, like animals, it was regarded as a symbol or manifestation of specific deities. 

When depicted, the moon is most commonly represented as a combination of the full-moon disk with the crescent moon. Lunar gods were almost always shown with this symbol on their heads. At times, the full-moon disk could have a wadjat eye (either the left or the right), or a lunar god depicted within it. The moon was, like the Sun, frequently shown traversing the sky in a boat. The most complete extant depiction of the entire lunar cycle is found inside the pronaos of the temple of Edfu.

The beginning of the lunar cycle was considered to be the new moon, and it ended with the moment of the full Moon. Therefore, the moon only became visible on the second day of the lunar month. The lunar cycle is represented either as a six day evolution up to the sixth day, or as a fifteen day evolution up to the ideal day of the full moon. The importance given to the sixth day is probably explained by the increasing intensity of moonlight at this stage of the cycle, though sometimes the seventh day is mentioned instead.

Interruptions in the usual lunar cycle were feared by the ancient Egyptians. A lunar eclipse was seen as a bad omen, evidenced from some Late Period texts that describe the sky swallowing the moon. The lunar cycle was also though to influence daily life, and the Egyptians dedicated stelae to it at Deir el-Medina, as well as forming personal names with the moon element. 

In time, the moon became a symbol of rejuvenation, and given it's cycle, this is understandable. Later texts in fact describes it as "the one that repeats its form". Sometimes lunar gods were depicted as youths, though the entire lunar cycle could be compared to the life cycle of a man. It could also represent the old man who becomes once more, a child. During the New Kingdom, a pharaoh might be declared "young as the moon", and Amenhotep III fully identifies himself with the moon in his temple at Soleb.

In funerary beliefs, the lunar cycle was an image of cyclical renewal. The feast of the sixth day was associated with the victory of Osiris, and even though the moment of the full moon could have the same significance, the sixth day became particularly important in funerary rituals. In fact, by the time of the Pyramid Texts, the deceased is already identified with the moon. During the Middle Kingdom, funerary beliefs were especially concerned with the night sky, even though lunar associations were not common during that period. However, the Coffin Texts from Deir el-Bersheh nevertheless accord an equal place in the afterworld to the lunar god Thoth, next to Osiris and Re. During the New Kingdom and later, the roll of the moon in the afterlife remains rare, but is found for instance in chapter 131 of the Book of the Dead. 

The moon also had other associations in ancient Egypt. For example, on account of the similarity in shape of the crescent moon and a bull's horns, it was compared to that that important animal. Hence, lunar gods are frequently described with "sharp horns". During the Greek period especially at Edfu and Karnak, the metaphor is developed by calling the crescent moon the "rutting bull", while the waning moon is an ox. Bulls in ancient Egypt were often seen as a symbol of fertility, and so the moon was "the rutting bull who inseminates the cows", but it was also said that "You unite with young women, you are an inseminating bull who fertilizes the girls", indicating a perceived relationship between female fertility and the moon. 

These concepts of fertility extend to resources as well, and the ancient Egyptians understood that there was a relationship that existed between the Moon and the growth of plants and that sowing was best done at the time of a full moon. However, it was even thought that minerals in the desert came into being under the Moon's influence. 

The moon and the sun were commonly referred to by the ancient Egyptians as "the two lights", and the weaker light of the Moon is compared to the evening Sun. Most frequently, the ancient Egyptians interpreted these two lights as the eyes of Re, or of the sky god Horus, whose left eye was the Moon and whose right eye was the sun. The left eye was weaker because it had been damaged, according to myth. This myth was elaborated upon in various cult centers, giving rise to special forms of Horus such as Khenty-Khety of Letopolis and the later Hor-Merty of Horbeit (in the Delta).

In fact, this mythology became very extensive, with a number of variants. Four primary myths can be identified surrounding the divine eyes. They included the eyes of the sky god, the injured eye of Horus, the solar eye and the distant goddess who is brought back. Variants of these myths were formed when elements form each were sometimes mixed and interchanged with the others.

By far, the predominant myth concerning the moon relates its cycle to the battle between Horus and Seth. In this famous battle over the inheritance of Osiris, Seth steals the eye of Horus and divides it into six parts, thus damaging it. Thoth later restores it "with his fingers", or by spitting on it. Within the temple at Kom-Ombo (scene 950), a series of medical instruments is depicted being used in the healing of the eye by the god Horoeris. This restored eye is called wedjat beginning in the New Kingdom, but the myth is actually much older and can be found in Spell 335 of the Coffin Texts. Onuris, Thoth, or Osiris as moon returns the complete eye to Horus. Thoth may also be said to catch the lunar eye in a net, acting together with the god Shu.

"Filling the Wedjat eye", "entering into the left eye", or "joining the left eye" also means restoring the eye. This act, which was performed by Thoth together with a specific group of fourteen gods,  was performed on the sixth lunar day. During the Greco-Roman period, temple reliefs form the region between Dendera and Esna indicate that the group of gods who restored the eye were the Ennead of Hermopolis. Together with Thoth, these gods represented the fifteen days leading up to the full moon, and again the days of the waning moon. As representing the latter, they are said to exit from the eye. At Edfu and Philae, the gods Tanenent and Iunit of the Hermopolitan Ennead are replaced by Hekes and Hepuy. 

A symbolic variant of this theme occurs in the temples at Edfu and Dendera, where a staircase with fourteen steps supports the fourteen gods of the waxing moon. At Edfu, Dendera and Ismant el-Kharab (Dakhleh Oaisis) there exist a list of a different group of thirty, mostly male, deities associated with the days of the lunar month. In these legends at Ismant el-Kharab, the first fifteen gods are said to fill the wedjat eye with a fraction each day, after which the moon's reduction is recorded up to the twenty-fourth day, when the intensity of the moonlight has all but disappeared. 

There were, of course, other important myths. Because of the identification of the moon with the god Horus, the birth of Horus (or Harsiese) was celebrated on the second lunar day in the ancient Egyptian month of Pharmuthi. Therefore, at Edfu where it is stated that "When he completes the half month, he assumes control of the sky rejuvenated", the full moon could be equated with the adult Horus. At the moment of the full moon, Horus was declared "true of voice" and "joyful", because of his victory over Seth in the divine tribunal of Heliopolis. Based on this theme, the lunar cycle was linked to the renewal of royal powers at Karnak.

The opposition of the Sun and Moon in the sky on the fifteenth or sixteenth day of the month was the most important moment of the lunar cycle. This is evidenced by inscriptions at temples in Edfu, Dendera and Karnak. This moment in time was known as "the uniting of the two bulls", and was described in the New Kingdom Osireion at Abydos. A ritual in later temples was celebrated with the offering of two mirrors, symbolizing the two lights at this precise moment. The moment symbolized the rejuvenation of the sun god Amun-Re at Thebes, and also in the Dakhleh Oaisis, when his son and successor, the moon god Khonsu, received his heritage of cosmic rule. 

Another important lunar god was Osiris, who may have only become identified with the moon as of the New Kingdom. The murder of the god Osiris and his resurrection were recognized in the lunar cycle, and the body of Osiris was equated with the moon. In this myth, Osiris' body was cut into fourteen parts by Seth, where were later reassembled and restored to life. Here also, the number of parts of Osiris' body were equated with the days of the waning or waxing moon. 

In other areas of Egypt, the entire life cycle of Osiris were related to the lunar cycle, with the god's conception on the first day and his birth on the second lunar day. At Karnak, the temple of Pet was actually dedicated to this event. Osiris' murder and subsequent dismemberment were associated with the  period following the full moon. Hence, the second day of the month saw the reassembly of the god's parts and his "entering into the moon" on the sixth day. The rejuvenation and the defeat of the god's enemies occurred on the day of the full moon, when Osiris was declared victorious in the tribunal, and when Horus was awarded with his heritage.

The name of the lunar god Khonsu relates to the verb which means "moving in various directions". This characterizes the lunar orbit, and particularly in the earliest references, Khonsu is given an aggressive nature. Later Theban sources tell how Khonsu traveled every day from the east (his temple at Karnak) to the west (the temple of Djeme), in order to revitalize his deceased father, Amun. Specifically, it is the Theban theology that describes the moon god as the son of the sun god.

There were a few other gods with specific links to the moon, including Min and the Greek form of Isis. Goddesses were usually only associated with the moon when they were identified with the eye of Re, as were Tefnut and Hathor. The annual journey from Dendera to Edfu by the Hathor cult statue was timed in accordance with the phases of the moon.

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