In the book of Philippians, we're told over and over again to rejoice, because it is safe to do so in any situation, and because there are so many enemies to it. Here we address a big one head on: The "legal spirit," where I do what I do in order to gain favor with God (or someone else).

Resources:

Philippians 3:1-16

Philippians (Baker Exegetical Commentary on the New Testament), Moises Silva

The Whole Christ, Sinclair Ferguson