Those things are the “wonders” because the Lord has destroyed what is strong by what is weak, the wisdom of the world by the folly of the cross, the things that are by the things that are not, glorious things by base things (1 Cor. 1:27 f.) For thus says the Lord in Matthew: “What is exalted among men is an abomination in the sight of God.” Hence, since this psalm is in the mouth of spirits and of mystical youth, its historical meaning is altogether spiritual. The Spirit speaks mysteries or mystical and hidden things, as Ps. 78:2 says. Matthew cites: “I will utter things hidden from the foundation of the world” (Matt. 13:35), for these mysteries were and are hidden from the princes of the world. And this is the wisdom which the apostle speaks in mysteries. Therefore you must beware of interpreting the words in this psalm according to the killing letter and the flesh.
Luther’s works, vol. 10: First Lectures I