Paul Leopold sent me the link to a review published in 1955 in TSL.
Below you can read a few fragments. The full review HERE.
For, of all the popular Christian apologists of the present day, Professor Lewis has been the most accessible and acceptable to a sceptical and suspicious generation. Those readers with whom he has had his most spectacular success – the intelligent but uninstructed free-thinking, free-believing young men and women of the war years – had little knowledge of theology. Many of them naively, though honestly, thought that Christians remained Christians merely because they had closed their eyes to the evidence of science and psychology, because they were unaware of the difficulties of belief. In the author of The Screwtape Letters, on the other hand, they found one who knew all about those difficulties. He had asked the questions which they, too, asked, and he knew only too well the kind of answers which they themselves had tried to give. A young ordinand has been known to put Screwtape aside, saying: “This man knows too much about the Devil.’’ It is certain, at any rate, that he knows a good deal about young men.
It might have been expected, therefore, that the shape of Professor Lewis’s conversion would follow that of the conversion which he has effected (or failed to effect) in others; that the arguments which had convinced him would be those by which he had tried to convince them. In fact, his story is quite different. Professor Lewis, not without precedent, found his arguments after he found his faith. Those who have read his eloquent demonstration that we must take Jesus as God or take him not at all may be surprised to find here so very little reference to the Incarnation.
“I was driven to Whipsnade one sunny morning [he writes]. When we set out I did not believe that Jesus Christ is the Son of God, and when we reached the zoo I did.”
It is the kind of remark which might have won a prize in the “This England” column of the New Statesman and Nation. But it has the unmistakable crispness of integrity. The author is really trying to tell the truth about himself. If Defoe had had to describe his own conversion instead of describing those of others he might have written very like that.