Justification by Faith Alone was the rallying cry of the Reformation. The main point that caused Luther and Calvin to challenge the Catholic Church and it's teachings.
God has a righteous basis for our justification through the sacrifice of His Son, for our sins. Grace was not cheap for God. Christ paid a great debt by pleasing God's wrath, both in metaphysical pain and human pain of the crucifixion (Lev. 16; Psalm 103:12). Our independence is a slap in His face, and He can do nothing in us until it is removed (John 3:5)! Let us pray to be cleansed by the atoning death of our Savior, who bore our punishment and lived out the law on our behalf.
Some Jews take issue with this saying it is umbilical that God cannot over rule His own law sighting Duet. 25:1 and Prov. 17:15; however they do not realize that Jesus Himself is the righteous One and He lived a perfect life in our place, as a designated hitter.
The Catholic Church taught that justification was a process through the sacraments and church, and that faith contributed to it as well as works. The reformers said this act was done at once at our acceptance of His gift of grace. The Catholic Church at the time of the reformation was even 'selling indulgences' granting people a spot in Heaven for money regardless of faith or even the church. They did this to pay for the cathedrals they were building, and you thought bingo was bad! Although Catholic apologist say this was never an 'official act' of the church. Nevertheless history clearly states this was a wide problem.
© 1992, 2001 Rev. R.J. Krejcir, Schaeffer Institute of Church Leadership, www.churchleadership.org/