It is impossible to write upon the theme which this book sets itself without using the terms Catholic and Protestant in the conventional sense. The words stand for certain historic magnitudes. It is equally impossible to conceal from ourselves how misleading the language often is. The line between that which has been happily called the religion of authority and the religion of the spirit does not run between Catholic and Protestant. It runs through the middle of many Protestant bodies, through the border only of some, and who will say that the Roman Church knows nothing of this contrast? The sole use of recurrence here to the historic distinction is to emphasise the fact that this distinction stands for less than has commonly been supposed. In a large way the history of Christian thought, from earliest times to the end of the eighteenth century, presents a very striking unity.
In contrast with this, that modern reflection which has taken the phenomenon known as religion and, specifically, that historic form of religion known as Christianity, as its object, has indeed also slowly revealed the fact that it is in possession of certain principles. Furthermore, these principles, as they have emerged, have been felt to be new and distinctive principles. They are essentially modern principles. They are the principles which, taken together, differentiate the thinker of the nineteenth century from all who have ever been before him. They are principles which unite all thinkers at the end of the nineteenth and the beginning of the twentieth centuries, in practically every portion of the world, as they think of all subjects except religion. It comes more and more to be felt that these principles must be reckoned with in our thought concerning religion as well.
One of these principles is, for example, that of dealing in true critical fashion with problems of history and literature. Long before the end of the age of rationalism, this principle had been applied to literature and history, other than those called sacred. The thorough going application of this scientific method to the literatures and history of the Old and New Testaments is almost wholly an achievement of the nineteenth century. It has completely altered the view of revelation and inspiration. The altered view of the nature of the documents of revelation has had immeasurable consequences for dogma.