Charles H. Spurgeon on Psalms 55:19

Because they have no changes, therefore they fear not God. That is, there is no new thing among them, no extraordinary providential turns, no judiciary changes, their prosperity keeps a settled course, and because they find all things going on in the old course of providence, therefore they go on in their old course of sinfulness, they fear not God; intimating, that as such changes always should, so usually they do, awaken fear; and that, if the Lord would but change, and toss, and tumble them about, by various troublesome dispensations, surely they would fear him. Joseph Caryl.