Slideshow image

July 28, 2025

Testing Truth: What Isaiah Teaches Us About God's Word

by Jason Neill

Scripture reading: Isaiah 6; 9; 10; 36-37

In a world that often shies away from difficult truths, I find myself drawn to the refreshing honesty of figures like the prophet Isaiah, whose words cut straight to the heart of God's message. This is fortunately the case with all the prophets from Isaiah through Malachi. They all shared with their original audience exactly what God told them to say. Indeed, when God chose a person to be a prophet, they were to only share the literal words God gave them, hence the familiar phrase “Thus says the LORD” found in the prophets. This commitment to speaking God's literal words highlights the crucial role of a prophet, which Bible scholar Carl Laney further elaborates on: “The major role of the biblical prophets was that of royal diplomats who functioned as prosecuting attorneys on behalf of Yahweh. They indicted the people of Israel for their violations of the Mosaic covenant, called for repentance, and warned of coming judgment for continued disobedience.”

The origin of the office of a prophet can be seen in Deuteronomy 18:14-22. Since a prophet was delegated to speak the very words of God, a natural question would arise: how can we tell the difference between false prophets and genuine ones? Deuteronomy 18:21-22 says, “You may say to yourselves, ‘How can we know when a message has not been spoken by the Lord?’ If what a prophet proclaims in the name of the Lord does not take place or come true, that is a message the Lord has not spoken. That prophet has spoken presumptuously, so do not be alarmed” (NIV). Israel was encouraged to test any so-called prophet instead of believing anyone who would claim to speak for God.

To further understand the book of Isaiah, the reader must know that the nation of Assyria was growing in power. The spiritual decay of Israel (the Northern tribes) and its refusal to listen to God’s prophets caused God to send this nation as an instrument of discipline for violating the Mosaic covenant (see Deuteronomy 27-30; 2 Kings 17; Isaiah 10:5-19). Of course, Assyria had no idea they were being used by God (see Isaiah 10:7). Isaiah’s message to Judah (the Southern tribes) was to return to Yahweh and keep the covenant, which involved loving God with all their heart or eventually face the same circumstances as Israel (see Deuteronomy 6:5-25; Isaiah 3).   

Indeed, as Jesus put it so aptly, the entire Old Testament law can be summarized in two commands, “love the LORD your God with all your heart, all your soul, and all your mind. This is the first and greatest commandment. A second is equally important: ‘Love your neighbor as yourself’” (Matthew 22:37-39, NLT). It's important we understand God as depicted in not only this book, but both Old and New Testaments. God was ultimately after Israel’s affections, their heart. He wanted the nation to love him with their entire being (see Deuteronomy 6). That truth applies to us today. God is after our affections, our love. He wants us to love him and love our neighbor.

The Assyrian nation came close to invading Judah, but God miraculously delivered them (see Isaiah 36-37). While the Southern kingdom experienced periods with good kings who followed God, which postponed divine judgment, they were eventually invaded by the Babylonians in 605 B.C. due to its continued spiritual decline (see 2 Kings 18-25). The remaining portions of the book (chapters 40-66) are prophecies of comfort. They provide a glimpse of the Messiah and his coming reign.

Authorship and Date: The book is attributed to Isaiah, who began his ministry in Judah around 740 B.C. We know this because it coincides with the death of King Uzziah mentioned in Isaiah 6:1; King Uzziah reigned from 790 – 739 B.C. Isaiah’s ministry ended around 680 B.C. New Testament writers also attribute the book to Isaiah (see Matthew 3:3; 4:14-16; John 12:37-41; Romans 9:27-29; 10:16).

Jesus in Isaiah & Its Application: Several passages in this book reference Jesus. Predictions concerning him can be found in 7:14 (Matthew 1:22-23); 9:1-2 (Matthew 4:12-16); 9:6 (Luke 2:11; Ephesians 2:14-18); 11:1 (Luke 3:23, 32; Acts 13:22-23); 11:2 (Luke 3:22); 28:16 (1 Peter 2:4-6); 40:3-5 (Matthew 3:1-3); 42:1-4 (Matthew 12:15-21); 42:6 (Luke 2:29-32); 50:6 (Matthew 26:67; 27:26, 30); 52:14 (Philippians 2:7-11); 53:3 (Luke 23:18; John 1:11; 7:5); 53:4-5 (Romans 5:6, 8); 53:7 (Matthew 27:12-14; John 1:29; 1 Peter 1:18-19); 53:9 (Matthew 27:57-60); 53:12 (Mark 15:28) ; and 61:1 (Luke 4:17-19, 21).

Just as the nation of Israel was to test whether a prophet spoke for God, there is a modern application for Christians. We are encouraged to evaluate all truth claims against a standard, and that standard is the Bible. This is one of the reasons the Bereans were called “noble.” When the Apostle Paul and Silas shared the good news of Jesus of Nazareth, the Bereans “searched the Scriptures day after day to see if Paul and Silas were teaching the truth” (Acts 17:11, NLT).

The next time you hear someone say they speak for God, or offer some teaching using the Bible, test what they teach against Scripture. Ultimately, Isaiah’s timeless message continues to call us back to the heart of God, rekindling our affections for Him and His unchanging truth.