When the Lord exempted the gentiles from needing to practice physical practices that God gave the Israelites to do to help them understand the spiritual like fleshly circumcision, it caused an upheaval in the church we are feeling today. We are exempt from Jewish customs, but there is no scripture that defines what is a custom and what is something the Lord wants us to do.
To complicate it all, Constantine was instrumental in setting up church policy, and one of his orders consisted of "if the Jews do it, we are not to do it for the Jews are an evil people". He was the first to tell of the need to use Sunday as the sabbath, for example. Constantine was used mightily by the Lord, but as you can see Constantine did not know scripture.
The result of this is that if you study scripture as the true source of knowing God, there is a terrific amount of untangling to be done. Finding a church that is trying to untangle all this is very difficult.