I think it's obvious that you can't frame the gospel moralistically. That is, we tend to think of salvation in moralistic terms, going from a state of sin to a state of righteousness. But if our analysis in this series is correct, this moralistic framing isn't going to resonate with the post-Protestants. They are already saved. So telling them they aren't saved will just strike them as old fashioned, fire and brimstone, Bible thumping.
So what's the move? The move, in my opinion, is the link I noted in the last post, how the moralizing and politicizing of faith has fueled disenchantment. Specifically, while belief might be harder for us today disenchantment hasn't come without its costs. There are so many ways we're suffering due to disenchantment. We're all feeling a bit lost and unwell in this post-Christian world. We might be good people, but we aren't very happy.
That is the approach I take in my upcoming book Hunting Magic Eels: Recovering an Enchanted Faith in a Skeptical Age. Parts of the book are an attempt at this new approach toward evangelism, shifting away from a focus on sin toward our deep dissatisfactions with disenchantment, less a moral frame than a focus on unhappiness. I think that approach--"You may be good, but are you happy?"--is the new opening move for the gospel in a post-Christian world.