In the last episode, Miles visits a mountain in the Himalayas, where he is led to a "she" who is behind the God Account. It seems like it would make a lot of sense if Miles' mother, Ella Finer, is behind the God Account. I am not theorizing that she is alive, but that she has returned as an angel and is running the God Account.
For one, many friend suggestions are tied to Arthur's church, and many early friend suggestions have to do with helping parents connect with their children. In fact, after John Dove and Cara, this is the next friend suggestion Miles gets. Miles' friend suggestions are also intimately tied to his life, especially towards the end of the show, and do things for Miles that his mother would want to help him with, such as helping Ali and beginning to help restore Miles' faith.
Moreover, it is very clear that the God Account could not be run by a person. It knows and does things that would be impossible to know about, most obviously clueing in Miles on Ali's note in the last episode. I think this makes it clear that Corey Smith's code was stolen by an angel, Ella Finer, who is behind the God Account. And this is who Miles gets to see at the top of the mountain after the show ends, to be reunited with his mother after almost 20 years.
In one early episode, Rakesh suggests that the God Account listens to Miles through his phone. It doesn't seem that unlikely that the God Account does this, and it's probably through this that it knows exactly the right time to send Miles a friend suggestion or a like. This can explain many of the "coincidences" present throughout the show.
