The Screwtape Letters (1942) by C.S. Lewis

The safest road to Hell is the gradual one - the gentle slope, soft underfoot, without sudden turnings, without milestones, without signposts...

The Screwtape Letters is a satirical work of fiction that gives the reader a window into the spiritual world using the vantage point of a demon named Screwtape. In a series of letters to his young nephew, Wormwood, Screwtape instructs him in how to bring about the downfall of the young man he has been assigned to plague.
There are so many memorable passages and wise insights in this book. Often when we look at something from an opposing stance we are forced to see things we would not have seen from a position of agreement. This is the device C. S. Lewis uses in The Screwtape Letters and he does it exceptionally well.
He warns us that there are two equal and opposite errors we believe about devils. One is to disbelieve in their existence and the other is to believe and have an unhealthy and excessive interest in them. He reminds us that the devil is a liar and that Screwtape, himself, is not always seeing things truly.
Lewis said of this book that he’d never written anything more easily or with less enjoyment; that it was easy to twist his mind into a diabolical attitude but it was spiritually stifling. The world he had to enter ‘was all dust, grit, thirst and itch. Every trace of beauty, freshness and geniality had to be excluded.’

Some highlights of this book:

Men are killed in places where they knew they might be killed and to which they go, if they are at all of the Enemy’s party, prepared. How much better for us if all humans died in costly nursing homes amid doctors who lie, nurses who lie, friends who lie, as we have trained them, promising life to the dying, encouraging the belief that sickness excuses every indulgence, and, even, if our workers know their job, withholding all suggestion of a priest lest it should betray to the sick man his true condition!

Wormwood's 'patient' is a young unmarried man and the setting is at the start of WW2. Screwtape encourages Wormwood to turn the man's gaze on himself. He also advises him on ways to inculcate pride, selfishness, lust and fear in his patient and to exploit him during his dry spells:

Now it may surprise you to learn that in His effort to get permanent possession of a soul, He relies on the troughs even more than on the peaks; some of His special favourites have gone through longer and deeper troughs than anyone else...
He cannot ravish. He can only woo...
He leaves the creature to stand up on its own legs - to carry out from the will alone duties which have lost all relish. It is during such trough periods, much more than through the peak periods, that it is growing into the sort of creature He wants it to be. Hence the prayers offered in the state of dryness are those which please Him best...He wants them to learn to walk and must therefore take away His hand; and if only the will to walk is really there He is pleased even with their stumbles. Do not be deceived, Wormwood. Our cause is never more in danger than when a human, no longer desiring, but still intending, to do our Enemy’s will, looks around upon a universe from which every trace of Him seems to have vanished, and asks why he has been forsaken, and still obeys.

Whatever their bodies do affect their souls. Whenever there is prayer, there is the danger of His own immediate action.

In the last generation we promoted the construction of...'a historical Jesus' on liberal and humanitarian lines; now we are putting forward a new 'historical Jesus' on Marxian, catastrophic, and revolutionary lines.

Martin Luther said that 'the best way to drive out the devil, if he will not yield to texts of Scripture, is to jeer and flout him, for he cannot bear scorn.' Lewis uses his sharp wit and inspired imagination to open our eyes to the true nature of the spiritual world & to help us understand that there are spiritual beings whose purpose is to undermine our faith and prevent the formation of virtues.

I’d recommend The Screwtape Letters for ages 14 years and up. His writing appealed to my kids in their teens as he writes succinctly and with humour without sacrificing depth.