This and SWAN SONG by Robert R. McCammon are, I think, required reading for anyone interested in post-Apocalyptic fiction. Both deal with extreme end-of-the-world scenarios, both deal with bands of survivors coming together to find a way to deal with the harsh realities of a life beyond the one they grew up with.
Both are about, at their core, the question of good versus evil.
In the case of THE STAND, the bugaboo is Captain Tripps, a superflu that decimates the earth's population in a matter of months. Soon survivors are living alone, many of them unsure if there even ARE other survivors, scavenging foods from their neighbors' pantries, from supermarket shelves, from anywhere they can.
Of course, things don't stay "easy" or uncomplicated. There is a supernatural being called The Walkin' Man who is calling people together in the remains of Las Vegas, organizing them into a city, a population, a CIVILIZATION. There is no question that The Walkin' Man and his deputies are deeply, purely evil. They run a fascist government that brooks no dissent, no question.
At the other end of the spectrum is a loose group of (often bickering) survivors led by a counsel of men and women who mostly want to do what's right... but mostly have no idea what that right thing is, either. They are led spiritually by an old woman who is essentially a prophetess, a seer with one foot in this world and one foot in the beyond. This, of course, The Walkin' Man cannot abide, and the stage is set for a confrontation that will unreel in ways you won't see coming.
This is a huge book, ranging from around 900 pages to over 1200 depending on if you get the original published version or the unabridged version (both are worthwhile). But though grand in scope and vision, the central questions are small and simple, and resolved in one moment in a jail when an old man looks upon evil.