Most historians agree that the use of nuclear weapons on Japan saved lives on both sides. What’s the problem with that.
First of all, I have never seen evidence of "most historians" agreeing on that. I've seen a whole lot of sober, measured skepticism expressed by historians on that point.
It depends on whether they thought the Japanese were on the verge of surrendering before August 6, 1945 --- or not. I would not be the one to make the call on that, because I haven't got the military experience and expertise.
But some people DO have that kind of expertise. As the article points out,
"Six of the seven five-star generals and admirals of that time believed that there was no reason to use them, that the Japanese were already defeated, knew it, and were likely to surrender before any American invasion could be launched. Several, like Admiral William Leahy and General Dwight Eisenhower, also had moral objections to the weapon. Leahy considered the atomic bombing of Japan “barbarous” and a violation of 'every Christian ethic I have ever heard of and all of the known laws of war.'"
I don't think these American military leaders were pinkos, pacifists or fools.
"What’s the problem with that."
In terms of an ethic of killing, there is a difference between targeting soldiers/combatants/military assets, and civilians/noncombatants/civilian values.
Most people in the world today at least profess to recognize this distinction (except for ISIS and their ilk).
It's hard to put it any clearer than this:
" Any act of war aimed indiscriminately at the destruction of entire cities of extensive areas along with their population is a crime against God and humankind itself. It merits unequivocal and unhesitating condemnation." (Gaudium et Spes, para. 80, 1962)
Utterly crushing thre Japanese military/political machine would have been justice. Incinerating civilians with a deliberately indiscriminate weapon of mass destruction, was murder. That should be clear when you consider that General Douglas MacArthur and his staff wrongly succeeded in exonerating Emperor Hirohito and all members of the imperial family from criminal prosecutions.
Thus in the end, 250,000 civilians were killed, and the Emperor Hirohito was not.