Let’s read Daniel chapters 2 and 3, and Jeremiah 7, Jeremiah 8:1-3. Did you ever notice how close in time and close in proximity Daniel and Jeremiah were?
“Your threat means nothing to us. If you throw us in the fire, the God we serve can rescue us….But even if he doesn’t, it wouldn’t make a bit of difference, O king. We still wouldn’t serve your gods or worship the gold statue you set up.” (Daniel 3:16, 17, 18 MSG)
I think the fast (and the obedience and discipline that helped them complete it) gave them this strength and boldness. Even though God is angry in Jeremiah, He tells the people all He wanted:
“I did say this, commanded this: “Obey me. Do what I say and I will be your God and you will be my people. Live the way I tell you. Do what I command so that your lives will go well” Jeremiah 7:23 MSG
So simple, all He asked for was obedience and relationship. Again, His intention was always kind, but it was man’s sin that created the consequences.