Westminster Project 1.9-10

9. The unerring rule of interpretation of Scripture is the Scripture itself. Therefore, when there is a question about the true and full sense of any Scripture (which is not multiple, but one), it must be searched and known by other places that speak more clearly. 

10. The supreme judge by which all controversies of religion are to be determined, and by which all decrees of councils, opinions of ancient writers, doctrines of men, and private spirits are to be examined, and in whose judgment we are to rest, can be nothing other than the Holy Spirit speaking in Scripture. 
(WCF 1.9-10)

Have you ever had a conversation with another believer where two differing opinions on a theological subject came up? Perhaps you’ve even heard the phrase, “Well, that’s just your opinion.” On one hand, it’s wonderful to have deep, robust discussions about theology. On the other hand, we must be careful not to base our doctrine solely on personal opinions, but rather on God’s revelation.
Why? 

Because, as we’ve seen over the weeks, the Bible is God’s preserved Word to us (Matthew 5:18, 2 Timothy 3:16-17, 2 Peter 1:20-21). Since it is God’s Word, it is objectively true and without error (Psalm 119:89, John 17:17). Therefore, when it comes to matters of life and doctrine, it’s our responsibility as God-fearing people to dig deep and carefully consider what God reveals to us. We must search the Scriptures and draw conclusions based on God’s revelation so that we may worship Him in spirit and in truth (John 4:23-24, Acts 17:11-12).

That said, this doesn’t mean we should reject the teachings of Bible teachers or church doctrine passed down through the ages. Far from it. Christ, through the Holy Spirit, has been building His church for thousands of years (Matthew 16:18a). Over those years, God has raised up incredible teachers and theologians to help illuminate the wonderful truths of Scripture for His people (John 16:13, Ephesians 4:4-13).

History shows us many instances when believers held differing opinions about God. Yet God raised up faithful leaders at crucial times so that the truth of Scripture would prevail and set people free, just as He promised (Matthew 16:18b; see also Acts 15:1-29).
For example, in the 4th century, the Arian controversy arose. Some taught that Jesus was a created being and that “there was a time when the Son was NOT.” Yet faithful Bible teachers—especially Athanasius—defended the truth, grounded in the whole counsel of Scripture, that “there was NEVER a time when the Son was NOT.” This truth was ultimately affirmed in the Nicene Creed.

Similarly, in the 5th century, the Pelagian controversy emerged. A British monk named Pelagius taught that humanity did not inherit sin from Adam and was therefore born sinless, able to cooperate with God’s grace to achieve final justification (a view known as synergism). But God raised up Augustine to defend biblical truth. Augustine showed—again from the whole counsel of Scripture—that we are not merely spiritually sick but absolutely dead because of Adam’s sin. Therefore, God’s grace is not something we can cooperate with; rather, it is the very power that reaches into spiritual death and brings life (a doctrine called monergism, see John 1:4-5, Romans 5:12-21). This truth was affirmed by the Council of Ephesus.

All of this illustrates that whenever the universal visible church has faced error or threats, God has raised up leaders to defend and define His truth, guiding His people. The creeds, councils, and teachers that have stood the test of time are not built on the shifting sands of human opinion, philosophy, or blind tradition—but on the ROCK of Jesus Christ and the teaching of His Prophets and Apostles (Ephesians 2:20, 3:5).