"Let us unfold the tale of the ancient past. Why was our father Abraham blessed? Was it not because he acted in righteousness and truth, prompted by faith? Isaac, fully realizing what was going to happen, gladly let himself be led to sacrifice. In humility Jacob quit his homeland because of his brother. He went to Laban and became his slave, and to him there were given the twelve scepters of the tribes of Israel. And if anyone will candidly look into each example, he will realize the magnificence of the gifts God gives.
For from Jacob there came all the priests and the Levites who serve at God's altar. From him comes the Lord Jesus so far as his human nature goes. From him there come the kings and rulers and governors of Judah. Nor is the glory of the other tribes derived from him insignificant. For God promised that "your seed shall be as the stars of heaven." So all of them received honor and greatness, not through themselves or their own deeds or the right things they did, but through his will. And we, therefore, who by his will have been called in Jesus Christ, are not justified of ourselves or by our wisdom or insight or religious devotion or the holy deeds we have done from the heart, but by that faith by which almighty God has justified all men from the very beginning. To him be glory forever and ever. Amen." [italics mine]
Clement of Rome, Letter to the Corinthians (c. AD)
Compare this with the following Canons of the Council of Trent:
CANON 9: "If any one saith, that by faith alone the impious is justified; in such wise as to mean, that nothing else is required to co-operate in order to the obtaining the grace of Justification, and that it is not in any way necessary, that he be prepared and disposed by the movement of his own will; let him be anathema."
Canon 24: "If any one saith, that the justice received is not preserved and also increased before God through good works; but that the said works are merely the fruits and signs of Justification obtained, but not a cause of the increase thereof; let him be anathema."
To be sure, Clement's exposition lacks the polemical edge of Luther (naturally), but he clearly excludes acts of devotion or pious deeds from our justification, which for him is by a faith that has its source in God. There was indeed a lot of water under the bridge between Clement's time and the Council of Trent, but I suspect the assembled bishops gathered at Trent under the authority of the Pope would have been - along with Luther - loathe to admit that history relativizes doctrine, and their position is clear: faith alone is anathema and good works contribute to justification. Which presents our Roman Catholics with an interesting question: who was right, Clement or Trent?