God's children have rebelled against him, they no longer know him, they are sinful, they have forsaken him, despised him, they are utterly estranged from him. They are in a bad state - in a desolate country with burned out cities, overthrown by other nations
What is God's message? Stop the false religion. He's had enough of the sacrifices, doesn't delight in the offerings, can't endure their assemblies, hates their feasts, wont listen to their prayers. They are doing the practices that God told them to do but their hearts are not in it, shown by their lack of justice and compassion on the weak.
So what does it look like for people to rebel against God? It could look like open blasphemy and blatant sin. But it could look like this - people keeping all the religious rules and expectations - never miss church, kids in sunday school, committed to all the special activities at Easter and Christmas, financially contributing to the church, serving on a few committees but without a heart that loves God. Doing those things is not bad, but its becomes bad if you think that by them you are pleasing God. It becomes bad if you think that those thigns excuse your lack of love for others. They become bad if they are just part of a life that is centered on you.
If you're a respectable rebel, repent and turn to God.
“Come now, let us reason together, says the Lord:
though your sins are like scarlet,
they shall be as white as snow;
though they are red like crimson,
they shall become like wool. (Isaiah1:18)