It is evident that in many passages this psalm from the Holy Bible exhibits a striking similarity to Aton's Hymn. Could it then be a case of plagiarism by the Bible writer's or was it mere coincidence?

I'm not familiar with the bible, I'm afraid.

OK - nice I could be useful. But just to throw a spanner in the works, I would argue that Akhenaton was not a monotheist, but an atheist or possibly the first humanist. When you look at the development of religious thought in Egypt, the concept of the sun being at the centre and pinnacle of the cosmological organisation was not new. But what Ahkenaton developed was the concept that it was the energy WITHIN the sun that was important, not any anthromorphised God. He seemed to realise that it was that specific energy which gave not only earth its life, but also the universe. He tried to steer Egypt away from worshipping effigy gods, which always seemed to need appeasing - usually with money or goods !!

And of course he was waging (unsuccessfully) against the increasing power of the priesthood at Thebes, and the worship of Amun, which had been steadily increasing since the repulsion of the Hyksos.

But everyone seems content to see him as a disabled eccentric.

Only my own view of course -you wont find Redford agreeing!

It's extremely difficult to said with some authority those things that Akhnaten did or did not do. He has been described--by different people, of course--as an atheist, a "dreamer", a very intelligent man who, seeing the take-over of the Amun priesthood with their growing power did his best to stop them, a man who believed that he, and only he, was in contact with his god.
His idea of establishing a new capital worked, his banning of most of the older god did not. Evidence is quite clear the the people in Amarna continued with the worship of the old gods in secret, in their homes.
The period in which he lived is, in my opinion, one of the most interesting, and also one most unknown, of all of the dynasties. The 18th, 19th and even some of the 20th dynasties are very confusing, to say the least.
I know you can't claim that Akhnaten started the worship of the Aton. There is clear evidence that his father, Amenhotep III, was one who brought the worship of the Aton forward. And the Aton was an old god!
As I say, the study of Akhnaten and his family is confusing, to say the least.

check out touregypt, Akhnaten. It has much more information:
The mythology of the Aten, the radiant disk of the sun, is not only unique in Egyptian history, but is also one of the most complex and controversial aspects of Ancient Egypt.

The ancient Egyptian term for the disk of the sun was Aten, which is first evidenced during the Middle Kingdom, though of course solar worship begins much earlier in Egyptian history. It should be noted however that this term initially could be applied to any disk, including even the surface of a mirror or the moon. The term was used in the Coffin Texts to denote the sun disk, but in the 'Story of Sinuhe' dating from the Middle Kingdom, the word is used with the determinative for god (Papyrus Berlin 10499). In that story, Amenemhat I is described as soaring into the sky and uniting with Aten his creator.

Text written during the New Kingdom's 18th Dynasty frequently use the term to mean "throne" or "place" of the sun god. The word Aten was written using the hieroglyphic sign for "god" because the Egyptians tended to personify certain expressions. Eventually, the Aten was conceived as a direct manifestation of the sun god.

Though the Aten became particularly important during the New Kingdom reigns of Tuthmosis IV and Amenhotep III, mostly sole credit for the actual origin of the deity Aten must be credited to Amenhotep IV (Akhenaten). Even at the beginning of the New Kingdom, it's founder, Ahmose, is flattered on a stela by being likened to "Aten when he shines". His successor, Amenhotep I, becomes in death "united with Aten, coalescing with the one from whom he had come". Tuthmosis I was portrayed in his temple at Tombos in Nubia wearing the sun disk and followed by the hieroglyphic sign for 'god'. Hatshepsut used the term on her standing obelisk in the temple of Karnak to denote the astronomical concept of the disk, though it was actually during the reign of Amenhotep II that the earliest iconography of Aten appears on a monument at Giza as a winged sun disk (though this was a manifestation of Re) with outstretched arms grasping the cartouche of the pharaoh.

Later, Tuthmosis IV issues a commemorative scarab on which the Aten functions as a god of war (a role usually reserved for Amun) protecting the pharaoh. Amenhotep III seems to have actively encouraged the worship of Aten, stressing solar worship in many of his extensive building works. In fact, one of that king's epithets was Tjekhen-Aten, or 'radiance of Aten', a term which was also used in several other contexts during his reign. During the reign of Amenhotep III, there is evidence for a priesthood of Aten at Heliopolis, which was the traditional center for the worship of the sun god Re, and he also incorporated references to the Aten in the names he gave to his palace at Malkata (known as 'splendor of Aten'), a division of his army and even to a pleasure boat called 'Aten glitters'. Also, several officials of his reign bore titles connecting them with the Aten cult, such as Hatiay, who was 'scribe of the two granaries of the Temple of Aten in Memphis. and a certain Ramose (not the vizier) who was 'steward of the mansion of the Aten'. The latter was even depicted with his wife going to view the sun disk.

Prior to Amenhotep IV, the sun disk could be a symbol in which major gods appear and so we find such phrases as "Atum who is in his disk ('aten'). However, from there it is only a small leap for the disk itself to become a god.

You're an info-genius Osiris II Thank you ever so much