Even with two atomic bombs and the Russian invasion of Manchuria, Japan still faced an attempted military coup when they considered surrendering.
Man, as an outsider looking in, it seems like the propaganda program surrounding the atomic bomb is astoundingly effective. Everyone regurgitates the same arguments, the fact that its contentious in the history and ethics communities seems to be glossed over completely.
The bombings of Nagasaki and Hiroshima weren't even the most deadly of the war. The US had burned most of Tokyo to the ground and more was coming.
Japanese citizens were going to die in masses when the invasion force hit the beach. Either sacrificing themselves in suicide attacks, or being used as human shields.