How did Paul refute the false teaching that Gentile Christians must become Jewish proselytes?

When the early church decided that gentiles did not need to become proselytes (Acts 15), saying some have said "Ye must be circumcised, and keep the law: to whom we gave no such commandment:

28 For it seemed good to the Holy Ghost, and to us, to lay upon you no greater burden than these necessary things;

29 That ye abstain from meats offered to idols, and from blood, and from things strangled, and from fornication: from which if ye keep yourselves, ye shall do well. Fare ye well.

Paul said that Jesus abolished the laws that separated Jews and gentiles (Eph. 2:15), and both Jews and gentiles knew that Jews kept dietary rules that gentiles did not; meats were one of the primary customs that separated them. Therefore, when the early church allowed people to live like gentiles (1 Cor. 9:21; Gal. 2:14), they were saying, in effect, that they could eat the foods that gentiles normally ate. The Levitical instructions about clean and unclean were rules for ritual and ceremony, not for defining sin and morality.