Back in the Middle Ages, theologians had nothing but Sin on their minds - they saw Satan lurking around every corner, tempting us to fall. Nowadays, though, it’s mainly Disbelief that God’s got to worry about. Oxford don C. S. Lewis spotted that trend back in 1941, when The Screwtape Letters appeared serially in The Guardian newspaper.

Well, things haven’t changed in 75 years, which makes the current New York Off-Broadway presentation of The Screwtape Letters still totally relevant. Set up as a series of letters from a crafty senior devil counseling a junior soul-stealer, it makes for a captivating one-man show for Max McLean, who’s carved out quite a niche for himself in such faith-based theatricals as Mark’s Gospel and Genesis.

It's not totally a one-man show, actually; McLean’s joined on stage by Karen Eleanor Wight, playing his attendant imp Toadpipe. Besides giving the audience something extra to look at - this is a VERY wordy piece - she manages not only to enact all the other parts and carry off stage business, but to convey the degraded animality of pure evil. Slithering around a distinctly dank and dungeon-like set, her creepy pantomimes brilliantly counterpoint Screwtape’s bombastic rants. I’ll give director Jeffrey Fiske an A+ for stagecraft alone.

But here’s the big question: Who is the audience for this piece? It’s possible to ignore the Christian allegory in Lewis’s Chronicles of Narnia and read it as a straight children’s fantasy, but The Screwtape Letters is an unapologetic argument for Christianity – very entertaining, no question, but still out-and-out God propaganda. And though the production’s staged in a church – the Theater at St. Clements – it’s a church that long ago converted to an Off-Broadway theater six days a week. This production has to succeed dramatically, not just preach to the choir.

The play’s producers, Fellowship for the Performing Arts – bless their hearts - are devoted to producing “theater from a Christian worldview that is engaging to a diverse audience.” If that’s your broad goal, it seems to me, you can’t assume that the audience members have all read C. S. Lewis. The production could have done more – a little dumbshow at the beginning, at least – to set up the play’s premise. It’s tricky to adjust to the fact that when Screwtape says “Our Father” he means Satan, and “the Enemy” is God. It’s confusing even on the written page; on stage, it can be just plain baffling for the first half-hour of this 90-minute production.