(This is an excerpt from The Infinite Atonement by Tad R. Callister..
Why was it essential that the Atonement be performed by Jesus, who is “infinite and eternal” (Alma 34:14)? Because the Atonement required power, incredible power, even infinite power. It required power to resurrect the dead, power to conquer spiritual death, and power to exalt an ordinary person to the status of a god. Such power could be exercised only by a being who was infinite, meaning a being who possessed all divine virtues in unlimited measure, and was therefore a God.
The Infinite Atonement, Tad R. Callister, p. 73