From Mark Booker
Psalm 38: Sin promises life but delivers death. Verses 3-8 give us a picture of the physical effects of sin in the psalmist's life. We shouldn't conclude from this psalm that sickness can mechanically/automatically be linked to sin in our lives - that's a problematic view (see John 9.3). But, in a more general sense, Psalm 38 shows us that sin makes us unsound physically, emotionally, spiritually, and we can all attest to that in our lives. This is the natural outworking of sin, but it is also, according to the psalmist, a result of the wrath or anger of God at his sin (vv.1-2). To experience the burden and consequences of sin, either from its natural outworking or from God's personal agency or both, is a kind of grace. Our misery in sin leads us to forsake and confess our sins. That's where it leads the psalmist, as he confesses his sin (v18) and appeals to God for help and rescue (vv.21-22). And we know, especially from the cross of Jesus, that God always stands ready to forgive.
Psalm 39: This psalm is a cry for help from a place of trouble. It rebukes our infatuation with human achievement and accomplishment and offers a sober assessment of our lives. They are 'fleeting' (v4) and a 'mere breath' (v5, 11) and subject to futility. The psalmist, like Job, sees God as the source of his suffering (see Job 7.17-21, 10.20-22, 14.1-6) and despite acknowledging that his hope is in him (v7) asks for God to look away from him (same verb as in Job 7.19). This is not a simple rejection of God but an honest wrestling with the difficulties and realities of life before God, much like the book of Job. In the end, God is there - the psalmist is after all speaking to him! - and embraced even amidst the complexities and pains of this world. This psalm is a model of active, wrestling faith.
Isaiah 44.9-20: This section mocks the fashioning of idols from the stuff of creation. The height of this folly is saying to something in creation (an image fashioned from iron, money, sex, power, a spouse, a career), "Deliver me, for you are my god!" (v17). Lifeless idols cannot save. Only Yahweh can. He is the only God (see v6 and Dt 4.32-40) so we are to put our trust in him, to obey him, to follow him.