Screwtape gives the sub-devil, Wormwood, instructions to ensure that the person entrusted to him ends up in Hell. When that person chooses Jesus Christ, the instructions get really subtle because now the enemy, God, is more obviously involved.
The classic ‘The Screwtape Letters’ by C.S. Lewis has was hard to read for me, in terms of content and language. I had already thought the latter, since C.S. Lewis held a chair in English literature at Oxford and Cambridge and the book was first published in 1942.
The book is written as a collection of letters. In terms of content, it provoke and stimulate thinking. Although the book was written in 1942, the themes can easily be located in the present day.