Visitor: Some people quote Old Testament "rules" about some things while they sit there on the Sabbath eating shrimp while wearing blended fiber clothes that cover a cute tattoo of an American flag. All of those things being forbidden by the same book they're using to condemn something else.....
Response: Forbidding the eating of shrimp was one directive for the Jews to be set apart from the unclean Gentiles as God's holy people. Jesus fulfilled the law and now He includes Gentiles, incorporating them into God's kingdom as well. When Jesus was crucified all that separated Jew and Gentile was done away with including these theocratic laws to separate them from Gentiles (Ephesians 2:11-20). Gentiles are accepted now in Christ, having been formerly unclean .... recall Peter's vision on his rooftop seeing the sheets of animals come down (Acts 10:9-16) which God said he could now eat ... because God was showing him that He now accepted Gentiles coming into the kingdom. God declared “What God has made clean, do not call common.” (Acts 10:15). So understood properly there is very good reason these practices were changed. Gentiles were unclean and are now included among Abraham's offspring because of Christ (Acts 9:28; Galatians 3:29). Without understanding this background to your statement it just sounds like some arbitrary change of law. But It actually has deep significance for the New Covenant which the Old Testament itself promised all along (Genesis 22:18; Ezek 36:26) God did not change. This was his redemptive plan through the whole bible from the beginning.