Augustine of Hippo

"And the earth was moved and trembled" [Psalm 18:7]. When the Son of Man was thus glorified, sinners were moved and trembled. "And the foundations of the mountains were troubled." And the hopes of the proud, which were in this life, were troubled. "And were moved, for God was angry with them." That is, that the hope of temporal goods might have now no more establishment in the hearts of men.

Exposition on Psalm 18 ↗

Thomas Aquinas

"It was moved." Above the Psalmist treated the affection conceived from the benefits of deliverance; here he treats the power of the deliverer. The power of an agent is shown from the agent's effect; and the things said here can pertain to a twofold effect of God: namely to the one shown in corporeal things, and to the effect of redemption. And perhaps more truly to both, because the things said here under the figure of corporeal things are spiritually fulfilled through the effect of redemption. …

Exposition on the Psalms of David ↗