From Mark Booker
Psalm 90: Book four of the psalms begins with a psalm that acknowledges the hardship, futility, and brevity of life. These realities are understood as the consequences of sin, the result of God's wrath. "You return man to dust" (v3). "You sweep them away as with a flood" (v5). "For we are brought to an end by your anger" (v7). "For all our days pass away under your wrath" (v9).
And yet, from the outset God is affirmed as 'our dwelling place' (v1) and appeals are made to his pity (v13) and steadfast love (v14) and for his favor (v17) - not because we deserve it but because of God's grace. God's people know, even when experiencing God's judgment for sin, that his character is weighted to mercy and grace (see Exodus 34.6-7 - in fact the entire story of Exodus 32-34 [people sin, God's wrath is provoked and experienced, God's mercy is appealed to, given, and revealed] is an appropriate backdrop for this psalm, which, incidentally, is the only psalm attributed to Moses). To this merciful character David famously appeals in Psalm 51.1-2. And the psalmist appeals to God in a similar way here (vv12-17). Our hope is in God alone. Only God can teach us (v12), satisfy us (v14), make us glad (v15) and establish the work of our hands (v17).
Psalm 91: This is a confident psalm that celebrates God's protection in the midst of any and every circumstance. It inspires trust and peace in the midst of whatever challenges we face (like Ps 46). It balances the psalms of protest and lament (e.g. Ps 74, 79), and in some ways it directly answers the concerns of Ps 90.10 with human transience (the two psalms are linked by the rare expression 'dwelling-place' in 90.1 and 91.9). "With long life I will satisfy him, and show him my salvation" (v16). This is fulfilled ultimately by the never-ending life that Jesus offers us, "Everyone who lives and believes in me will never die" (John 11.26).
Romans 3.1-24: Paul shows that all - Jews and Greeks - are under sin (v9). "All have sinned and fall short of the glory of God" (3.23). We deserve nothing but judgment, as we saw in this past Sunday's sermon on Deuteronomy 9. But we are justified (made right, declared to be in the right) "by his grace as a gift, through the redemption that is in Christ Jesus." Our life in God is a gift, enabled by Jesus' death. By declaring that we are all under sin, Paul is magnifying God's grace/gift, leveling the playing field, and eliminating human boasting (v27). The only proper response is humility and praise.