In a passage [from his 1964 book The New Creation] that should have tipped off the Dominican censorswho, a year later, would send him to Cambridge to edit New BlackfriarsMcCabe compared communism to the heavenly city. Just as the Marxist looks forward to...the final withering-away of the state, he wrote, so the Catholic looks forward impatiently to the withering-away of the organized church.That analogy, with its bold eschatological affinities, reflects the paradox of McCabes career: a vibrant orthodoxy wedded to a revolutionary political vision. Much of McCabes subsequent work lay in showing that it was truly a paradox and not a contradiction. ...McCabes socialist commitment was bound up with his devotion to the gospel and the church; almost all his remarks on politics appeared in reflections on theological matters. In his essays and sermonsand especially in Law, Love, and Language (1968), his most lengthy and compelling reflection on ethicshe explained and advocated revolutionary change in terms of orthodox theology, not as its repudiation, but rather as its fulfillment.
You can see both sides of McCabe at work in an article he wrote for Commonweal in 1966, which we've just posted online: "The Validity of Absolutes: An Answer to the New Moralists." It's a formidable defense of the concept of moral absolutes against "situationist ethics" -- and McCabe ends his argument by quoting Marx.