Paul rebukes Peter for his hypocrisy and how his actions don't communicate the truth of the gospel to Jews and Gentiles. The grace of God motivates people to obey God based on total undeserved acceptance and contrasts legalism, where acceptance before God is based on our works or by obeying the law. The gospel pardons sinners by justifying based on Christ's righteousness and unites us with Christ, allowing us to live radically new lives based on a new identity in Christ. Living lives based on being pardoned by God's grace will be characterized by genuine love, gratitude, and a positive focus because of God's mercy.