Romans 1:22-23 — Professing themselves to be wise, they became fools, and changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.
Man broke the first Commandment when he invented his own divinity and placed it above God.
Man broke the second Commandment when he fashioned God as an animal.
Foolishness is a departure from knowledge of God, not a stage in the development of knowledge. In other words, fools are on the way down, not on the way up.
Change — Man cannot change God, but they exchanged His glory for another.
Glory = everlasting power and divinity (verse 20) that was revealed through creation.
Made like = likeness. Man exchanged the real thing for an image.
In the Old Testament, Israel (which knew God) was ridiculed for turning to idols. In the New Testament, Gentiles who grew up with idols are taught but not ridiculed.
Corruptible = subject to rust and decay. (Not "mortal" as translated in the NIV.)
Man > birds > beasts > reptiles — a progression of degredation