Final answer:
The doctrine articulated by Martin Luther, signifying that salvation could be attained only through faith in God's grace and not by good works, is known as Justification by Faith. This formed a key tenet of Protestantism, differing from the Catholic Church's belief in the necessity of combining faith with good works for salvation.
Step-by-step explanation:
Martin Luther's reading of the New Testament led him to the conclusion that "good works" were not sufficient or required for salvation. Instead, what was necessary was a belief in God's love and mercy. The term that reflects this belief in salvation through faith alone is Justification by Faith. This doctrine was revolutionary at the time because it contradicted the Catholic Church's teaching that salvation was achieved through a combination of faith and good works.
The Catholic Church advocated the idea that performing good deeds could help one attain salvation, for instance, through the commissioning of art for the Church or buying indulgences. Luther challenged this by interpreting St. Paul's words "The just shall live by faith" (Romans 1:17) to mean that salvation is a gift from God granted through faith alone. Justification by Faith became a foundational doctrine of Protestantism, setting it apart from the Catholic tradition.