Martin Luther was a famous 16th century German theologian. He wrote his summary of Lutheran doctrine for a 1537 ecumenical conference. Luther summarized his philosophy as follows "The first and chief article is this: Jesus Christ, our God and Lord, died for our sins and was raised again for our justification (Romans 3:24-25). He alone is the Lamb of God who takes away the sins of the world (John 1:29), and God has laid on Him the iniquity of us all (Isaiah 53:6). All have sinned and are justified freely, without their own works and merits, by His grace, through the redemption that is in Christ Jesus, in His blood (Romans 3:23-25). This is necessary to believe. This cannot be otherwise acquired or grasped by any work, law, or merit. Therefore, it is clear and certain that this faith alone justifies us... Nothing of this article can be yielded or surrendered, even though heaven and earth and everything else falls (Mark 13:31." From the preface, "The first part of this book presents the studies of the Author in preparing a Memorial Oration delivered in the city of New York, November 10, 1883, on the four hundredth anniversary of the birth of Martin Luther. The second part presents his studies in a like preparation for certain Discourses delivered in the city of Philadelphia at the Bi-Centennial of the founding of the Commonwealth of Pennsylvania."