Day 30 of 40 covers Daniel, Hosea, Joel, and Amos and is all about God and human kingdoms.

"Despite the hurt, God remains committed to His people. Yes, He must discipline them - tearing them like a lion - but His committment to restoring the relationship is as sure as the rising of the sun at dawn and the rain showers in the spring ([Hosea] 5:14-6:3)." (Dr. Timothy Berrey, "40 Days Through The Bible")