Calvin vs. Luther starting point?

"Now I wish to be second to none in my praise of Luther's heroic initiative. In his heart, rather than in the heart of Calvin, was the bitter conflict fought which led to the world-historic breach. Luther can be interpreted without Calvin, but not Calvin without Luther. To a great extent Calvin entered upon the harvest of what the hero of Wittenberg had sown in the clearest insight into the reformatory principle, worked it out most fully, and applied it most broadly, history... points to the Thinker of Geneva and not to the Hero of Wittenberg. Luther as well as Calvin contended for a direct fellowship with God, but Luther took it up from its subjective, anthropological side, and not from its objective, cosmological side as Calvin did. Luther's starting-point was the special-soteriological principle of a justifying faith; while Calvin's extending far wider, lay in the general cosmological principle of the sovereignty of God. As a natural result of this, Luther also continued to consider the Church as the representative and authoritative 'teacher,' standing between God and the believer, while Calvin was the first to seek the Church in the believers themselves.” Abraham Kuyper – Lectures On Calvinism