Final answer:
The Protestant Reformation in Christianity began when Martin Luther objected to the Catholic Church's sale of indulgences in 1517 and taught that faith alone was needed for salvation. This led to the emergence of different Protestant churches and a break from the Catholic Church.
Step-by-step explanation:
The Protestant Reformation in Christianity began when Martin Luther, a German monk, publicly objected to the Catholic Church's sale of indulgences in 1517. Luther's ideas spread throughout Europe with the help of the printing press, and he taught that faith alone was needed for salvation and that scripture was the only source of Christian authority. The Protestant Reformation led to the emergence of various Protestant churches and a break from the Catholic Church.