Exodus 34, Psalm 36, Matthew 15:21-39, Acts 21:27-40

Psalm 36:

Why people act the way they do is a fascinating topic. Why do we act the way we do? It has driven the concerns of psychology, history, sociology, and much else besides. Have you ever wondered why it is that you do certain things or what it is that is really motivating you? Or perhaps you have wondered why it is that people can reject God or act in ways that are plainly-so it appears to us-wrong, even evil?

The first part of this psalm describes the morphology of sin. What is really going on? How does someone, made in the image of God, commit barbarity? After all, “Transgression speaks to the wicked deep in his heart” (36:1). There is something called conscience. But “there is no fear of God before his eyes.” Without the fear of God as a present, felt reality, people act in ways that are against even their own conscience deep within their own heart. What is more, the person deceives themselves. “He flatters himself in his own eyes that his iniquity cannot be found out and hated” (36:2). His self-talk is of self-approval. He invents excuses for his behavior. It is inevitable that such and such must be done; there is no other alternative. And so both words (36:3) and plans (36:4) are increasingly anti-God.

Why does it matter why people act in this way? Because it is important that we know the tendency of our own heart to write excuses for ourselves, and because we can be wise about the way people can excuse evil deeds. There are few things more dangerous than being naïve about the power of sin and evil to deceive. As God said to Cain in Genesis 4:7, “sin is crouching at the door. Its desire is contrary to you, but you must rule over it.” We must fight against our natural tendency to excuse evil actions.

As William Gurnall, author of the famous Christian in Complete Armour, advised: Christians are to even sleep in their spiritual armor. The sword of the Spirit—the word of God—the shield of faith, the helmet of salvation, the breastplate of righteousness, and all the pieces of armor are held together by the belt of truth. Do not stop fighting sin, for if you do, you are sure to lose the fight. As the Puritans would say, be killing sin, or sin will be killing you.

The second half this psalm, though, from verse 5, changes perspective. It is rather depressing to only think about the power of sin to deceive ourselves. David also thinks about the power of God’s love to redeem, save, and strengthen us. This “steadfast love” (36:5, 7, 10) is what gives him the confidence and the power to keep on going. Think on the love of God.

If it is naïve to not realize the power of sin, it is a mistake to fight sin without reflecting on the love of God. Are you convicted of sin? Do not think that God therefore does not love you. He loves sinners! In fact, it was while we were still sinners that Christ died for us. His love “extends to the heavens,” his faithfulness “to the clouds” (36:5). You can’t overestimate the love of God. Look at the cross! There is love, vast as the ocean.

What is more, this love is itself motivating. The more holy we are and the closer we are to God, the more we realize the sheer pleasure of knowing God! You “feast on the abundance of his house” and you “drink from the river of his delights” (36:8)! That’s no boring, mundane, tired existence! That’s life to the full in the here and now, and life forever too. “For with you is the fountain of life; in your light do we see light” (36:9)!

So David concludes by praying that he would experience God’s steadfast love, that the “foot of arrogance” and the “hand of the wicked”-so often together, arrogance kicking and wicked hitting-would not drive him away (36:11). And he knows that, in the end, the evildoers outside of God’s grace will “lie fallen” and “unable to rise” (36:12).