Galatians 3 talks about how God supplies His Spirit through hearing with faith. It emphasizes the fact that we are justified by faith and not by following the law. It says that the law was our "custodian" or "guardian" until Christ came, but we are now justified by faith in Him. Paul also highlights the fact that all who believe in Christ are children of God, and that there is no distinction between Jews and Gentiles. Overall, the chapter stresses the importance of faith in Christ and how it transcends the boundaries of the law.