The Protestant Reformation was a time of debate over the core beliefs and structure of the church. The main idea for Martin Luther and those like John Calvin (the father of the Reformed tradition the Presbyterian Church is a part of) is that we are saved by God's grace through faith alone. The Roman Catholic point of view is that our good works are also part of our salvation. This passage from James was very important in supporting the Catholic argument. Of course, like most arguments, both sides overstated their disagreements. Catholics believe faith is important and Protestants believe that faith leads to good works. No matter what tradition we identify with we know that God calls us to live our faith, which is what James is saying.