New Testament writing addressed to Christian churches (exact location uncertain) that were disturbed by a Judaizing faction within the early Christian church. The members of this faction taught that Christian converts were obliged to observe circumcision and other prescriptions of the Mosaic Law. They repudiated Paul's statements to the contrary by denying the legitimacy of his apostolic calling. In rebuttal, Paul vigorously defended his credentials as a true apostle of Jesus Christ and provided important autobiographical information in the process.

In the letter Paul reaffirms his former teaching that the Mosaic Law is obsolete and that a return to Jewish practices would therefore be regressive. Though Christians have a new freedom, they have no license to sin; rather, they assume a responsibility to live lives in accord with the Spirit of God. Historical problems have caused uncertainty about the date of the letter's composition.