Remember, the Israelites carried idols with them throughout their time in the wilderness (Amos 5:25-26; Acts 7:42-43). Their idols seemed good to them, but the true God did not. God's way of life undoubtedly seemed devilish - it was chaffing and constraining, which is one reason they always complained. They did not see the true God as a force for good in their lives. They believed He was bent on their destruction (Deuteronomy 1:27-28). Joshua rebuked Israel because, as he said, serving the true God seemed evil to them (Joshua 24:15)! The Israelites accepted Baal, Molech, and other demons, and yet, as Stephen told the council during his trial, the fathers always resisted the Holy Spirit (Acts 7:51).
That syncretistic festival also rhymes with what God says in Amos 5. He says, I hate, I despise your feast days, and I do not savor your sacred assemblies. . .. He says, Take away from Me the noise of your songs, for I will not hear the melody of your stringed instruments (Amos 5:21-23). A few verses later, God says that even as they were making sacrifices to Him in the wilderness, they also had other gods. And then He says, Therefore I will send you into captivity . . . (Amos 5:25-27). In another chilling rhyme, 40 of the revelers were taken into captivity on their feast day.
There is no indication that they were not keeping the holy days of God. But there was something about these people, that God did not consider it to be "His." It was now "theirs." They were keeping it in a self-centered way, according to their own way.
Well, they were offering sacrifices and offerings.
