I believe Christianity did experience a renewal in the POST war years (of which little trace can now be seen). This was due in no small part to men being hung out over the burning pit of hell (in what they had experienced in the War)
I can tell you for a fact that Christianity in Germany was in a shambles prior to WWII. This was largly because of post WWI existentialism and theological liberalism (Germany being the center of the storm). Austria also.
Why do you think Hitler was able to so easily transfer such intense devotion to himself? It was because people had lost sight of Christ.
***It saved the West from Communism***
But not Socialism - right?
***Church attendance was high--somewhere around 80%.***
Church attendance figures do not necessarily reflect the state of devotion in the heart of a people.
I will grant that Germany had unique problems stemming from World War I, but I would hardly call it the center of Christianity nor of the Church at that time. In any case, it was the abruptness of the collapse of the Church after the Council that is so startling and noticeable--the precipitousness of the decline that is so stunning. No one doubts that the twentieth century was a furious cauldron of mutual hatreds and vice as you indicate--but the Church was in the thick of the fray every step of the way, not giving an inch either to Communism or Nazism. Vocations rose exponentially during this period. Mass attendance held steady somewhere in the high 70 percentile. Missions flourished. Even the popular culture reflected a respect that today would amaze young people--Fulton Sheen was a television star who was more popular than Milton Berle. On the Waterfront was a distinctly Catholic movie--and it was a critical and popular success, winning many oscars. Nor was it an isolated phenomenon. Sound of Music, the Cardinal, The Ten Commandments--all were big hits at the time. So I don't buy any of what you say. It was the Council that caused the abrupt declines in the Church--and at an expedited rate. And the collapse was systemic and in every single category measuring institutional health. All this happened within ten years of the close of Vatican II. There is no getting around it.