Can you clarify if converted Jews that are now part of the church are supposed to keep the law? I’m not referring to the sacrifices, but to the feasts, kosher eating, observance of the Jewish calendar. Some family members who are Christian are now part of a Messianic congregation and they acknowledge salvation through Jesus, are now only eating kosher, keeping their feasts, and say we are drafted into Israel and the early church members were Jews that still kept all of that.
I know there are Messianic Jews who choose to keep at least part of the Law. It’s like they have one foot in the Old Covenant and one foot in the New. The question is whether they just want to follow the tradition to learn from it, which is OK, or whether they’re trying to either complete or maintain the work of their salvation, which is not. Any path to salvation that combines grace and human effort is destined to fail because it ultimately leaves us responsible for our own salvation. Romans 3:20-22 says no one will be declared righteous by observing the Law, but only by receiving the righteousness that comes through faith in Jesus Christ. You can’t have it both ways.
Paul wrote that regardless of background, a member of the Church is no longer considered either a Jew or a Gentile (Galatians 3:28). He also said not to let anyone judge us by what we eat or drink, or with regard to religious festivals, new moon celebrations or sabbath days. He said these were a shadow of things to come but the reality is found in Christ (Colossians 2:16-17).