Final answer:
Akhenaton declared monotheism by making Aton-Ra the supreme god and ousted other deities, designating himself and Queen Nefertiti as the only intermediaries between the god and the people.
Step-by-step explanation:
When Akhenaton declared Aton-Ra as the supreme god, he also declared an end to the worship of the traditional Egyptian pantheon, thereby instituting monotheism. This religious reform also designated the pharaoh and his queen, Nefertiti, as the sole intermediaries between Aten and the people, effectively ousting the powerful priesthood and changing the spiritual landscape of Egypt. Akhenaton not only closed temples of other gods and destroyed representations of them but also established the capital at Amarna, where he and his queen became the chief priests in the cult of Aton.