We can see in hindsight that the war was lost at Atlanta, but that was far from clear at the time. We can see this in the sense of panic that Lincoln, Stanton, and even Grant seemed to feel at the prospect of a Confederate army moving into Tennessee (Stanton was especially concerned about the Union's fiscal situation, worrying that they would no longer be able to pay for the war if it lasted much longer). In November of 1864, Hood had never even heard of a place called Appomattox and thought he still had everything to fight for.
Fun Fact: When John C. Breckinridge was summoned to Richmond in January of 1865 to be appointed Secretary of War by Jefferson Davis, it caused a flurry of discussion among people about whether this made him the chosen successor of Davis and the natural shoe-in to be elected the second President of the Confederate States in the 1867 election. . . while Lee's army was starving in the trenches of Petersburg and the fall of Richmond was a mere three months away.
To us, all this seems silly, but that's only because we know the war is going to be over in a few months. The folks in late 1864 didn't know that.