How do we know the doctrine of God's word is true?

The truth of God's doctrine is established through its divine authorship and the transformative effects it has on believers. As stated in 1 Thessalonians 2:13, when we received the word of God, we accepted it not as the word of men, but as it is in truth, the word of God, which effectually works in those who believe. This effectiveness and power of the word in our lives affirm its truth. Additionally, the Bible reveals that God’s word does not change, remaining the same yesterday, today, and forever, which strengthens our conviction in its truth.