But while we thus find in the Son of God and in His atoning work the foundation of the faith of our Church, many obstacles had been placed in the way of securing this redemption.  Legalistic conditions made it impossible for the sinner to know that his sins had been taken away.  It was here that the Lutheran Reformation pointed the way to a return to the simplicity of the Gospel by its Scriptural definition of justification. Sola fide, by faith alone, was the keynote of the Reformation.  Be sure that you bring back sola was Luther’s admonition to his friends, who went to Augsburg while he himself remained at Coburg.

Thus justification by faith became the material principle of Protestantism and a second foundation stone of Lutheranism.  It is true that Calvin and the Reformed churches also accepted this principle, but they did not begin with it.  Their system was based on the idea of the absoluteness of God.  The Lutheran system emphasizes the love of God to all men; the Reformed system emphasizes predestination; which, by selecting some, excludes the others.  As the theologians describe it, Lutheranism is Christocentric, Reform is theocentric.*
     Calvin, like Luther, read theology through Augustine and without
his ecclesiology, but from an altogether opposite point of view.  Luther started with the anthropology and advanced from below upwards; Calvin started with the theology and moved from above downwards.  Hence his determinative idea was not justification by faith, but God and His sovereignty, or the sole and all-efficiency of His gracious will.-Ibid., page 162.

A third principle relates to the means of grace.  Here we have less difficulty in discerning the line of cleavage which separates us from Rome on the one hand and from the rest of Protestantism on the other hand.

The Lutheran Confession regards the word of God as the means of grace.  The Sacraments also are means of grace, not ex opere operato, but because of the word.  They are the visible word, or the individualized Gospel.  Hence, it is correct to say that the word, in the Lutheran system, is the means of grace.  This is doubtless news to many of our brethren of other faiths, who think of us only as extreme sacramentarians, and have looked upon us for centuries as Crypto-Romanists.  Nothing could be further from the truth.  It was only by an accident that the emphasis of polemical discussion in the sixteenth century was laid upon the sacramental question, where it never belonged.

In her doctrine of the means of grace, the Lutheran Church differs toto coelo from Rome.  It is not the Church which, through its authority and its institutions, makes the means of grace effective; but it is through the means of grace that the Church is created and made both a product and an instrument of the Holy Ghost.