It was and is a marvellous system; there has never been anything like it and if it should wholly fail from amongst us there will never be anything like it again. And yet we see that all this vast spiritual edifice, like the arches of its own great cathedrals, locks up upon a single keystone. The keystone of the arch of Catholic certainty is the acceptance of the authority of the Church conditioned by belief in the divine character of that authority. If anything should shake the Catholic's belief in the authority of his Church and the efficacy of her sacraments then he is left strangely unsheltered. Strongly articulated as this system is, it has not been untouched by time and change. To continue our figure, one great wing of the medieval structure fell away in the Protestant Reformation and what was left, though extensive and solid enough, is still like its great cathedrals--yielding to time and change. The impressive force and unity of contemporaneous Catholicism may lead us perhaps to underestimate the number of those in the Catholic line who, having for one reason or another lost faith in their Church, are now open to the appeal of the newer movements. For example, the largest non-Catholic religious group of Poles in Detroit are Russellites. There are on good authority between three and four thousand of them. _The Protestant Church Made Faith the Key to Salvation with Conversion the Test for the Individual of the Reality of His Religious Experience_ If religion has been made real to the Catholic through the mediation of his Church, Protestantism, seeking to recreate the apostolic Church, has made the reality of religion a matter between the individual and his God. And yet Protestantism has never dared commit itself to so simple a phrasing of religion as this, nor to go on without authorities of its own. Protestantism generally has substituted for the inclusive authority of the Catholic Church the authority of its own creeds and fundamentally the authority of the Bible. As far as creeds go Protestantism carried over the content of Latin Christianity more largely than we have generally recognized. Luther was in direct line with Augustine as Augustine was in direct line with St. Paul, and Luther's fundamental doctrine--justification by faith--was not so much a rewriting of ancient creeds as a new way of validating their meaning for the individual. Faith, in our common use of the term, has hardened down into an intellectual acceptance of Protestant theologies, but certainly for St. Paul and probably for Luther it was far more vital than this and far more simple. It was rather a resting upon a delivering power, the assurance of whose desire and willingness to deliver was found in the New Testament. It was an end to struggle, a spiritual victory won through surrender.