If we DO ever get a Good Omens season 3 (and fingers crossed we will) then using the Second Coming as the narrative device to facilitate the final culmination of Good Omens' ideology and message is brilliant, actually.

Because the Second Coming IS NOT another Adam situation. And, contrary to the misconceptions I've seen, It IS NOT about Jesus being born again as a baby, etc, etc.

THE SECOND COMING. QUITE LITERALLY refers to THE LAST JUDGMENT.

As in. The SAME Last Judgment Michelangelo painted on the walls of the Sistine Chapel. As in - THE JUDGMENT of the Living and the Dead. THE LAST, FINAL, ETERNAL JUDGMENT.

It's the WHOLE thing Armageddon was leading towards. Book of Revelation speedrun: the world ends, everyone dies, and then they get resurrected again to be judged by JESUS himself. He will flick through the Book of Life (WINK WINK WINK DO YOU SEE HOW LOUDLY I'M WINKING AT YOU???), and if your name is there he will go "oh nice you deserve eternal paradise! :D" and if your name is ERASED from the Book of Life he will go "oh no, sorry, you go to the lake of fire for eternity now D:" (except apparently in Good Omens lore it'd just DOOM YOU TO NON-EXISTENCE FOREVER???)

And if you THINK about it, The Last Judgment is the ultimate manifestation of moral absolutism. No shades of gray, no chances. Just BLACK, and WHITE. Never mind that you're like Wee Morag and Elspeth, who are forced to do "bad" things because of circumstances. It's either you pass Judgment Day, or you burn (or disappear forever.) And the way THINGS are going in the Good Omens universe? I don't think there's ANYONE "good" enough to be "saved." Not Crowley, not Aziraphale. Hell, not even the Archangels themselves.

So it provides a PERFECT opportunity for Aziraphale and Crowley to UPEND that SYSTEM entirely.

I think that's what Crowley and Aziraphale would do in s3: establish a new kind of system in which angels and demons have free will to determine the right (or wrong) choice.

Giving them the APPLE, so to speak.

And then they'll go off to retire in a cottage, together at last.