Christians in every age have acknowledged the importance of Paul's Epistle to the Romans. Martin Luther called it "really the chief part of the New Testament, and... truly the purest gospel." In addition, Samuel Taylor Coleridge regarded Romans as "the most profound book in existence" others have described it as "the cathedral of the Christian faith". The epistle is a Christian manifesto of freedom through Jesus Christ. It is the fullest, plainest, and grandest statement of the gospel in the New Testament. Throughout the centuries, this epistle has been recognized as perhaps the most complete theological statement regarding the Gospel of God. Paul is the great theologian who presented the gospel in theological terms which remain unmatched and which elevate the gospel message to a greater level of understanding. This epistle has five main themes: the first is the redefinition of the basis of salvation which is not based on the Law, but by grace alone and faith alone in Christ Jesus; the second is the redefinition of the people of God not according to physical birth but by spiritual birth and by faith; the third is the righteousness that is based on faith in God; the fourth is the doctrine of election; the fifth is the explanation of Christian behavior as based on Christian belief.