The atlas carries an entry for ancient Egyptian religion and an entry for Kemeticism, and they are not two accounts of one thing.
Ancient Egyptian religion was a state cult with an economy attached. Its temples held land, its priesthoods were offices, and the daily service of washing, clothing and feeding the god's image was performed in a sealed sanctuary by professionals acting for the king. It ran for well over three thousand years, changed considerably across that time, and ended: the temples closed under Christian Roman rule, the last dated hieroglyphic inscription at Philae belongs to the fourth century, and the knowledge of how to read the script was lost until Champollion recovered it in 1822.
Kemeticism begins in the 1970s. It is a reconstruction, and the good practitioners are precise about what that word concedes:
- The sources are texts and archaeology, read through Egyptological scholarship, not a transmission from a teacher who received it from a teacher.
- Very large parts of the ancient practice cannot be reconstructed, because the record preserves what was written on stone in tombs and temples and preserves far less of what ordinary people did.
- The ancient cult was inseparable from Egyptian kingship and the Egyptian state, neither of which exists.
Where a group claims unbroken descent from antiquity, the claim is not demonstrable and there is no evidence for it. That is a statement about the historical record and not a judgement about the religion; Wicca has the same history and most Wiccans now say so without regarding it as a loss.
The harder question is about Egypt. The sources are Egyptian, the sites are in Egypt, and the practitioners are overwhelmingly not: modern Egypt is Muslim and Christian, and there is no living Egyptian community with a claim on these gods. Kemetics disagree among themselves about what follows from that, and about the related question of the Ausar Auset Society and the Pan-African reading of Egyptian religion, which approaches the same material from a quite different starting point.