The Greatest battle being fought is the spiritual battle between light and darkness. Some give in and neglect to fight so ultimately, they are given over to diverse evils easily & there are others who are in battle constantly against themselves to serve the Most High God and his goodness. A non believer is a servant to their sin, while a believer is at war with their sins. It's a big difference between the two and the second has a greater end result. This one is for the believers, those who seek out the learning of the Lord, and those who may not understand the battle that comes with serving the Heavenly Father.