Just to show that the Reformers did not invent justification by faith alone, here is a very old (and perceptive) perspective on Paul (AD 96):
Whosoever will candidly consider each particular, will recognise the greatness of the gifts which were given by him. For from him have sprung the priests and all the Levites who minister at the altar of God. From him also [was descended] our Lord Jesus Christ according to the flesh. From him [arose] kings, princes, and rulers of the race of Judah. Nor are his other tribes in small glory, inasmuch as God had promised, "Thy seed shall be as the stars of heaven." All these, therefore, were highly honoured, and made great, not for their own sake, or for their own works, or for the righteousness which they wrought, but through the operation of His will. And we, too, being called by His will in Christ Jesus, are not justified by ourselves, nor by our own wisdom, or understanding, or godliness, or works which we have wrought in holiness of heart; but by that faith through which, from the beginning, Almighty God has justified all men; to whom be glory for ever and ever. Amen.
Letter to the Corinthians chapter 32