The book of James demonstrates how vast a change true faith brings to the life of a saint.
In James chapter 2, you are taught that true faith makes a vast difference in how you treat the various people at church each week (2:1-7).
Furthermore, true faith also makes a difference in how you think about yourself compared to the evildoers in society (2:8-12) and how true faith will always lean towards mercy (2:13).
True faith makes a difference, because, well, that is what true faith does (2:14-20)! It was true for the saints of old (2:21-25), and is really simple to understand (2:26).
True faith makes a difference. Is your faith dead, or alive?