God sent a warning through the prophet Isaiah because his people didn't want to hear the truth. They told the prophet to prophecy to them smooth things, they didn't want him to speak on their sins, they encouraged him to speak to them lies, and wasn't concerned about how God felt about it. Unfortunately we're living in an era where the people of God are just like that. People want to heart sermons that will satisfy their fleshly appetites and God wasn't pleased with it then, and He's not pleased with it now.