The American Spectator, a conservative journal, has an article by Tom Raabe marking the 90th anniversary of Evelyn Waugh’s conversion to Roman Catholicism on 29 September 1930. Raabe remarks that, at first, the conversion did not have much impact on Waugh’s writing, which continued with the comic satires he had begun with his pre-conversion novels Decline and Fall and Vile Bodies nor did his behavior change much:
Evelyn Waugh was in life everything that good Catholics, not to mention Christians in general, abjure, or are supposed to abjure. He was a short-tempered, rude, cranky, insulting, bibulous, intentionally unkind and insensitive man who didn’t much like his children and who, increasingly deaf in his later years, frequently carried with him an ear trumpet, nearly two feet long and comically old-fashioned, that he would raise to his ear when he was speaking and lower when he was spoken to. How can you not love a guy like that?
He may have continued to exhibit many of the same characteristics after his  conversion but with Brideshead Revisited in 1945 his writing changed. It was more what he wrote about than how he wrote it, but the change did not go down well with his critics. Raabe quotes to this effect Edmund Wilson, Joseph Frank, Kingsley Amis, Bridgid Trophy and Philip Toynbee.  According to Raabe, with Brideshead:
…Waugh departs from reliance on witty repartee (Ă la Ronald Firbank, an influence in Waugh’s earlier books), doesn’t include stand-alone humorous scenes, and brings the cast of characters into a religious milieu — the main characters are all set against a backdrop of faith. The patriarch of the central family, the Marchmains, and one son are wayward Catholics who, each in his own way, come back to the church in the end — one on his deathbed; the other, dissipated and repentant, at a religious house in Morocco. The mother and a daughter are as staunch in faith as can be; a different daughter is engaging in extramarital affairs but is wracked by guilt and eventually returns to the church. And the narrator, Charles Ryder, an atheist condemning Catholicism as “mumbo-jumbo” throughout, finds a spiritual home in the church at the end. Intellectuals dismissed the novel as a “Roman tract.”
It didn’t help that the Marchmains were aristocrats at a time when that became unfashionable among literary tastemakers. But Raabe is not persuaded that the wave of left-wing critical objections warrants a lower estimation of Waugh’s reputation . He concludes: “As all conservatives, Waugh possessed a realistic view of human nature, for we are all one step from barbarity without God’s grace.”