Having been studying in Psalm 46 this week in preparation for Sunday chapel services, I couldn't help notice the connection between Isaiah's promises in verse 10 and the Psalmist's words of hope and confidence.
Isaiah says, "Though the mountains move and the hills shake, my love will not be removed from you and my covenant of peace will not be shaken" (Isaiah 54.10, CSB).
The Psalmist cries in faith, "We will not be afraid, though the earth trembles and the mountains topple into the depths of the seas" (Psalm 46.2, CSB).
Most English translations make the connections and contrasts clear within verse 10 itself. The mountains might move, but the love/mercy of God will not be removed. The hills might shake, but God's covenant of peace will not be shaken. In other words, despite what is going on all around you--despite the chaos, uncertainty, and instability of the world and other people--God is entirely steadfast, dependable, and faithful. Everything around you might fail, but God will not fail. These connections are plain here in Isaiah, and it makes for a wonderfully comforting passage!
There is, however, also a not-so-obvious connection between this chapter in Isaiah and Psalm 46. Both inspired writers use the same Hebrew word (מוֹט / mot) describing the hills shaking, the mountains toppling, and the steadfastness of God's covenant. Psalm 46 takes things further and explicitly ties together God's faithfulness and might as our source of confidence, comfort, and hope in times of trouble. Where Isaiah's comfort is derived from God's promises to us, in the Psalm we are led like children to trust in God's refuge, strength, and help during difficult and frightening times. When everything is falling down around us, a direct connection like this one brings assurance and hope we most certainly need. It is a hope that allows us to sing out, even in hardships, "A mighty fortress is our God, A bulwark never failing!"