Final answer:
Believers are saved by 'Grace through faith', which is central to the Protestant doctrine emphasized by Martin Luther and John Calvin. They argued that salvation comes through faith alone, not through good works or religious observances. This was a key difference from Catholic teachings of that era.
Step-by-step explanation:
In Ephesians 2:8-9, believers are saved by Grace through faith, A) Grace through faith, not by trying to be holy or by keeping religious rules and regulations. This scriptural passage is foundational to the doctrine of salvation by grace alone, which Martin Luther and later John Calvin emphasized during the Protestant Reformation. Luther highlighted that human efforts and good works are insufficient for salvation; instead, faith alone in God's grace is the necessary condition. Similarly, Calvin's doctrine of predestination argues that God's all-knowing and all-powerful nature means that He chooses the elect according to His divine plan, rather than through human actions or free will.
Although Christians often demonstrate their faith through good works and participate in religious rituals and sacraments, such practices, according to Protestant theology, do not contribute to salvation. These views marked a significant departure from the Catholic Church's teaching, which held that good works played a role in achieving heaven.