Despite this effort, Luther returned to his home in Germany spiritually unsatisfied. Something was missing. But what had he missed and why was he spiritually unsatisfied? Deperate to find an answer, Luther turned to the epistles of Saint Paul. He carefully scrutinized each of Paul's letters. Then late one night he read a phrase that answered all of his questions: "He who is righteous through faith shall live." This was Luther's great moment of discovery. He suddenly realized that faith and faith alone was necessary for salvation. Faith was a gift freely given by God. Good works were what good people did but they were not necessary for salvation.
Luther's discovery soon reverberated throughout Christendom. Luther challenged the sale of indulgences,