How do we know sound doctrine is true?

Sound doctrine is recognized by its fidelity to the Scriptures and its adherence to the teachings of Christ and the Apostles. In 2 Timothy 4:1-2, Paul instructs Timothy to preach the Word, indicating that true doctrine must be grounded in biblical authority. The consistency of teaching across Scripture—from the Old Testament prophets to the New Testament epistles—affirms the reliability of sound doctrine. Furthermore, true doctrine produces fruits consistent with the character of God and leads believers into a deeper understanding of His grace and truth. This discernment comes through the illumination of the Holy Spirit, who guides believers to know and uphold the truth, safeguarding them against apostasy.