How do we know that Peter and Paul's teachings are true?

The relationship between Peter and Paul exemplifies the unity and consistency of apostolic doctrine. In 2 Peter 3:15-16, Peter refers to the wisdom given to Paul, recognizing his letters as Scripture, which affirms the inspiration and authority of both men. This affirmation of Paul's writings as equally authoritative as the Old Testament prophets shows us that their doctrines must be taken seriously. Furthermore, the transformative work of the Holy Spirit in the lives of believers serves as a testament to the truth of these teachings, as those who embrace the gospel live transformed lives marked by grace.