Who was Martin Luther and what was a core belief he held?

Martin Luther was a German monk and theologian who played a pivotal role in the Protestant Reformation during the early 16th century. A core belief he held was the doctrine of justification by faith alone, which asserted that faith in Jesus Christ is the only means by which individuals can achieve salvation. This belief was a fundamental challenge to the existing Catholic doctrine that included the necessity of good works and the mediation of the church.

Luther's emphasis on personal faith and direct access to scripture, particularly through his translation of the Bible into German, allowed individuals to interpret the Bible for themselves, breaking away from the authority of the Catholic Church. This led to significant changes in the religious landscape of Europe, encouraging a movement that valued personal belief over institutional authority.