...we now set out to explore the differences between Atenism and Jewish monotheism -- and here is where the road gets really rocky for the "borrowing" proponents.
1. Evangelism and exclusivism. Atenism was at its inception a typical Egyptian religion that "never bothered no one." Redford [Red.MA, 12] tells us:
It would never have occurred to an ancient Egyptian to postulate the supernatural as a monad -- a unitary, intellectually superior emanation. Much less would it have occurred to him to suppose that his eternal salvation depended on the recognition of such a monad. One man might choose to worship this god or that; another might even hold, for whatever reason, that other gods did not exist. But this was not important for an ancient Egyptian. He could not have cared less.
Akhenaten's monotheism, in line with this view, was neither evangelical nor exclusive. Aten became "the" god for the royalty; but he never became a god over the average Egyptian Joe, and in fact, "the degree of intensity with which the new program was pursued" went downhill "the farther one got from the royal presence." [Red.HK, 175] Akhenaten showed no interest in promulgating his faith -- not until it became to his political advantage to do so (like when the priests gave him trouble -- then evangelism became rather convenient).
2. Henotheism to monotheism.Of relation to this is the possibility that Atenism did not apparently begin as monotheism, but as henotheism -- preference and superiority of one god over others. The earliest inscriptions of Akhenaten continue to refer to "gods" in the plural -- this may be because Akhenaten himself has not clarified his beliefs yet, or it may be that sculptors needed some time to get used to the idea of using the singular. [Red.MA, 22]
A key here is an inscription which says that all gods other than Aten "have failed and 'ceased' to be effective." [Red.MA, 23] Does this mean that the other gods did once exist, but have been subjugated by Aten? Or does it mean they never really existed at all? The key verb is ambiguous. But it is possible that Akhenaten's thought underwent a sort of "mini-evolution" of it's own -- and note that it did not take thousands of years to happen!
3. Laws and ceremonies. We all know how many rules God handed down in the Pentateuch; what did Aten do that was the same? Actually, nothing. Atenism is "devoid of ethical content." [Red.MA, 113] As Redford puts it, while Aten is the creator (albeit with no associated "creation story"), he "seems to show no compassion on his creatures. He provides them with life and sustenance, but in a rather perfunctory way. No text tells us he hears the cry of the poor man, or succors the sick, or forgives the sinner."
Similarly, while we know all about the cultic apparatrus spelled out in detail in the OT, Atenism offered no cultic acts (other than a basic daily sacirifice), no cult images, no mythology, no concept of ever-changing manifestations of the divine world. [Red.HK, 169-70, 178] Atenism has more in common with the Deism of the 18th-century West than it does with Jewish monotheism.
4. Pharaoh as mediator. Atenism had this common link with "normal" Egyptian religion: Akhenaten was regarded as the sole mediator for Aten on earth. The idea of a mediator is in itself not unusual: Moses is portrayed as serving something of that role, and other religions conceived of their clergy as providing some level of intermediary service. But with Atenism, this relationship went so far as to make it so that the sun-disc of Aten was "simply the hypostasis of divine kingship, a pale reflection of [Akhenaten's] own on earth, projected heavenwards."
Akhenaten regarded himself as "ever the physical child of the sun-disc" and the sole high priest of Atenism. In further service of his own cult, the temples of other gods were closed, and their priesthoods were abandoned, including the funerary priesthood; as a result, the people literally (from their religious point of view) had to depend on Akhenaten for their fate in the afterlife. The focus on the pharaoh was so great that Allen [All.NP, 100] declares: "The god of Akhenaten's religion is Akhenaten himself."
Conclusion
Redford, who is regarded as the "foremost authority on Akhenaten" [Red.MA, 6] summarizes the view of Mosaic/Jewish monotheism being a ripoff of Atenism [ibid., 26, 113]:
...(T)hese imaginary creatures are now fading away one by one as the historical reality gradually emerges. There is little or no evidence to support the notion that Akhenaten was a progenitor of the full-blown monotheism that we find in the Bible...(it) had its own separate development.
...The monotheism of Akhenaten is so distinct from Yahwism that I wonder why the two are compared.
And Grimal [Grim.HAE, 228] adds:
It has been supposed that Atenism lies at the roots of Christianity, when in fact it does nothing more than reflect the common ground of Semitic civilizations.
Finally, Allen, quoting Assmann, observes that Atenism is "the origin less of the monotheistic world religions than of a natural philosophy. If this religion had succeeded, we should have expected it to produce a Thales rather than a Moses." [All.NP. 97] We would expect not the God of Judaism, but the Prime Mover of Aristotle, or the Deism of Thomas Jefferson, to come from the religion of Atenism.