The Platonism in Lewis' writing is not exactly concealed (check the Professor's refrain, "It's all in Plato" in The Last Battle), and nor does it seem to me at all dangerous - unless you reckon St.Augustine and Pope Benedict XVI dangerous. Platonism is, if not connaturate to the Christian religion (Irenaeus of Lyons and Thomas Aquinas, to quote only two giants, were not Platonists), at least a "recognized party". And I think that the essay you quote pushes the issue of Lewis' "barbs" against Catholicism much too far. For instance, about the passage about devotions to Saints, what Lewis has to say is nothing more than what many Catholic reformers have said down the years, indeed what the Vatican itself has backed by outlawing a number of outlandish devotions and derubricating several unhistorical saints. (If only they had got rid of the euhemerized pagan goddess St.Bridget!) As for the relevance of Tolkien's dislike of some features of Lewis' thought, while I appreciate (and indeed mentioned) the importance of "the ulsterior motive" in assessing Lewis' allegiances, nonetheless you have to remember that Tolkien was a very partisan kind of Catholic: a supporter of Franco, an avowed opponent of democracy, and a man who carried in his bones the rage of seeing his mother literally die of malnutrition because of the stone-hearted rejection by her Protestant relations. His Catholicism was considerably more partisan and exclusive than that of, say, GK Chesterton; almost to the point of being sectarian. Incredibly, he was not only pained by CS Lewis' refusal to support Franco in the Spanish Civil war - in which Lewis took the only possible course, damning both sides as tyrannical and vicious - but he actualy ascribed it to Lewis' supposed anti-Catholic prejudice, as if the only reason to disapprove of military tyranny and subversion were religious prejudice. Did Tolkien even realize that he was practically defending Oliver Cromwell and Napoleon?