Shmoopism. Has a nice ring to it! But we won't go there. Foster, on the other hand, is the founder of the Fosterite religion. On Earth, Foster founded his church on bully tactics and aggressive spreading of the faith. What was this faith?
"[Foster] borrowed from Freemasonry, Catholicism, the Communist Party, and Madison Avenue just as he borrowed from earlier scriptures in composing his New Revelation" (27.124)
Hmmm, a new religion that comes from the sampling of various other religions and institutions and transforming them to fit into a cohesive whole… sound familiar? Yep, Mike's Church of All Worlds takes a similar stance, drawing from Mike's experiences on Earth.
In the afterlife, Foster seems to have mellowed considerably. He guides the newly-deceased Digby toward a more angelic attitude, turning him into the Jubal of the afterlife. The nature of his work in the afterlife remains mysterious. And you know—we kind of like it that way.
In life, Supreme Bishop Digby is the head of the Fosterite religion. He's a pretty strict head honcho, too. Fosterites are told to "[a]lways look for that happy, holy seal-of-approval with Bishop Digby's smiling face on it" (14.23)—basically, what Digby says, goes.
That's a big no-no for Mike, and (surprise, surprise) Mike sends Digby to nonexistence. In the afterlife, Digby originally vows revenge on Mike, but through Foster's tutelage, he eventually becomes more angelic. After an away mission, Digby beings to lose his sense of identity or, at least, identity as he knew it on Earth. He eventually forgets his hatred for Mike, even to the point that he shakes Mike's hand when Mike becomes his new afterlife superior. Forgive? We're not sure. Forget? Absolutely.