Although The Stand is one of Stephen King's earlier works, it's also one of the most important in the King Multiverse. The world in which The Stand takes place appears later in The Dark Tower series, as does Randall Flagg, implying a direct connection to Gan and revealing the true nature of the conflict between Flagg and Mother Abigail.
Mother Abigail is a 108-year-old woman of Christain faith who appears to live in a world very similar to the real one. When she begins to hear messages from a seemingly divine source, she assumes that God is talking to her. She then visits people in their dreams, who are drawn to her and her conviction that she is doing the right thing. These people begin to build a new civilization called the Boulder Free Zone. Although some question Mother A's faith, they can't deny the shared dreams that brought everyone together.
On the other side, Randall Flagg draws his followers in much the same way. He visits some of them in their dreams and draws those to him with a more flexible sense of morality, rebuilding civilization in Las Vegas. He also attracts those who like strict law and order and those who follow power. Flagg puts draconian laws in place, including the banning of all recreational drugs and free speech, which is somewhat ironic given his chosen location of Las Vegas. The consequences for breaking the laws include torture and death. What's interesting is how similar Flagg and Mother A go about rebuilding civilization. Their approaches are much the same, both using powers they've mysteriously come by. Given this idea, one theory suggests they're both drawing power from and speaking to the same source.
Mother Abigail & Randall Flagg Are Speaking To The Same Source
One of the interesting things about The Stand is that neither Randall Flagg nor Mother Abigail really knows where their powers come from or why they are doing what they're doing. This is fine for Mother A, who frames her experiences within her lifelong faith in God, believing that God works in mysterious ways and that it is not her place to question His will. However, for Flagg, who seeks power and dominion, the source of his supernatural abilities is a bit more problematic.
When Flagg is first introduced walking down US highway 51 in the novel, he has memories of being a marine and a member of the KKK. He also remembers having a role in the kidnapping of Patty Hearst. However, he doesn't know much more than that. All he knows is that his time has come because his ability to do magic is growing. It appears that he hasn't yet begun to seek control over the Dark Tower and stop Roland Deschain in his quest to reach it. Either that or he has forgotten that part of his life as he forgets everything except for the events of the Superflu pandemic and beyond by the end of King's novel.
Given Flagg's ignorance of what he is and where he came from, it's quite possible that the same divine force that communicates with Mother Abigail is the same force guiding Randall Flagg's actions. In an interview for TV Insider, Benjamin Cavell, the showrunner for the latest screen adaptation of The Stand (CBS All Access), theorizes that they are actually communicating with the same force. If this is the case, this force is likely Gan, the creator of the various universes where Stephen King's novels take place, including the one in which King exists himself.
Who Is Gan? Stephen King Multiverse Creator Explained
Gan is the creator of the Stephen King Multiverse. That is, Gan brought into being every world that is featured in King's stories, up to and including the real world where Stephen King exists as a writer of those stories. The implication is that God and Gan are the same entity, or God is an aspect of Gan. Either way, Gan's role in the Stephen King Multiverse is very much in line with the concept of God.
In the sixth installment of The Dark Tower, Song of Susannah, Gan is described as emerging from the primordial nothingness knows as the Prim to create the Stephen King Multiverse and install the Dark Tower as the nexus connecting all possible worlds. Gan is directly opposed by the Crimson King, another powerful entity born out of Discordia that seeks to destroy the Dark Tower, thereby exterminating the entire King Multiverse as well as everyone and everything in it. Regarding The Stand, it's possible that Randall Flagg and Mother Abigail are chosen by Gan to facilitate the natural order of the universe, which is the infinite conflict between good and evil.
How Gan Could Be Controlling The Events Of The Stand
Given The Stand's connection to the Stephen King Universe, it's likely that the force communicating with Mother Abigail is actually Gan, although she frames her experiences around her lifelong Christain beliefs. Mother A claims that she has been chosen by God to bring together the survivors of the Superflu who are more "good" than "bad." She believes that God is speaking through her and is the entity that told her where to restart civilization (Boulder, Colorado) and who should be the Boulder Free Zone's initial leaders (Stewart Redman, Larry Underwood, Frannie Goldsmith, Nick Andros, and Glen Bateman). Despite this, she freely admits there are limitations to what she's being told and understands.
Randall Flagg, on the other hand, goes to great lengths to portray himself as all-seeing and powerful. He wants to believe that he knows what he's doing and why he's doing it, even though the truth is that he doesn't know any more than Mother A. In fact, in a lot of ways, he knows less. In The Stand, he has no memory of his childhood, how old he is, or even why he exists. He is driven to dominate, control, and sow chaos. If Gan is, indeed, the source of Flagg's powers, then the divine force works in mysterious ways.
The bottom line is that Gan is likely the force responsible for the events in The Stand. If the natural order of the universe involves the struggle between "good" and "evil," then Gan uses Mother Abigail and Randall Flagg to reenact the great conflict. It's possible that this battle has to happen in order for the survivors of the Superflu to learn how to build a better society, rather than simply restarting the old one. Of course, later Randall Flagg will seek to take control of the Dark Tower itself, retconned to play a larger role in the Stephen King Multiverse.