At one time you didn't know God. You were slaves to gods that are really not gods at all.
References for Galatians 4:8
But now you know God. Even better, God knows you. So why are you turning back to those weak and worthless beliefs? Do you want to be slaves to them all over again?
You are observing special days and months and seasons and years!
I am afraid for you. I am afraid that somehow I have wasted my efforts on you.