In Christianity and Liberalism , Machen acknowledged that “There are many who believe that the Bible is right at the central point, in its account of the redeeming work of Christ, and yet believe that it contains many errors.” Machen disagreed, but Machen did not believe that such views excluded them from fellowship: “Such men are not really liberals, but Christians; because they have accepted as true the message upon which Christianity depends. A great gulf separates them from those who reject the supernatural act of God with which Christianity stands or falls.”

Of Roman Catholicism, he wrote: “Far more serious still is the division between the Church of Rome and evangelical Protestantism in all its forms. Yet how great is the common heritage which unites the Roman Catholic Church, with its maintenance of the authority of Holy Scripture and with its acceptance of the great early creeds, to devout Protestants today! We would not indeed obscure the difference which divides us from Rome . The gulf is indeed profound. But profound as it is, it seems almost trifling compared to the abyss which stands between us and many ministers of our own Church. The Church of Rome may represent a perversion of the Christian religion; but naturalistic liberalism is not Christianity at all.”