"Sanctify Them in the Truth; Your Word is Truth."

Dr. Mark Bailey is the Dallas Theological Seminary Chancellor and Senior Professor in the Bible Exposition department.

Skepticism is not new. We live in a world influenced by human perceptions, personal preferences, and manipulation of impressions. We face a crisis of confidence in governmental institutions, public leaders, higher education, and news media. People wonder what truth means and where to find it. As Christians shining the light of the gospel in the world around us, we know that the biblical model of truth is both propositional and personal, revelational and relational. Exposure to truth demands a personal response. 

In John’s Gospel, the theme of truth is of critical concern. John 3:21 and 18:37–38 form bookends for his Gospel, highlighting the importance of a right response to truth as revealed in Jesus. The first states, “whoever does what is true comes to the light,” and in the second, Jesus states, “Everyone who is of the truth listens to my voice.” 

From John’s opening prologue to Jesus’s climactic interchange with Pilate, what is true about Jesus was on trial. The contest between the world’s opinion of truth and God’s view of truth is seen clearly in the exchange between Jesus and Pilate. That short passage in John 18:37–38 includes the affirmation of Jesus’s kingship, His claim to be the divine testimony to truth, and the judgment that people’s response to Him indicates their relationship to what is true. The echo of Pilate’s reactionary question “What is truth?” continues to resound today. 

We see the importance of rightly defining truth in Jesus’s high priestly prayer, the night before He went to the cross: “Sanctify them in the truth; your word is truth” (Jn 17:17). We might initially assume that the immediate referent is the Bible, and sanctification is the result. As conservative evangelicals with a high view of divine inspiration and the resultant quality of inerrancy, we rightly believe the Bible to be God’s truth in written form. But a closer look at the term truth in the context of John’s Gospel may yield a more focused understanding of this specific request. 

Of the four Gospel writers, John centralizes the theme of truth in relation to the Trinity, especially in the ministry of Jesus. God is said to be true (3:33 7:28; 8:26), the only true God (17:3). Jesus reveals the truth He “heard from God” (8:40). As the incarnate Word, Jesus is “full of grace and truth” (1:18). He’s the mediating channel who reveals grace and truth (1:14). The truth that Jesus taught and embodied can set people free from sin (8:32, 36). Jesus spoke the truth (7:18; 8:14, 16, 45; 16:7), and Jesus Himself is the very essence of truth (5:33; 14:6). The Holy Spirit is called “the Spirit of Truth” who dwelt with the disciples before the day of Pentecost and now indwells all believers (14:17). The Spirit is identified as a minister of truth because He was sent by Christ from the Father to bear witness to the truth (15:26) and to be a guide into all truth (16:13). He does not speak with His own authority. As John clarifies, what belongs to the Father belongs to Jesus, and the Spirit declares what belongs to Jesus, all to the glory of Jesus Christ (16:14). Therefore, the word of truth in the Gospel of John is centered on the person and work of Christ. 

In John 17, Jesus prayed that the disciples would be prepared to bear witness to Christ in a contrary world. The word sanctify means to set apart for a sacred use or service as designated by God. That passage mentions two sanctifications: that of Jesus and that of His followers. In a world hostile to the gospel, Jesus did not ask that His followers be taken out of the world but that they would be sanctified and protected as they’re set apart and sent into the world. To this end, Jesus said He will sanctify Himself, that the disciples would be sanctified in truth (17:15–17). 

The self-sanctification of Jesus was His willing submission to all that the Father consecrated Him to do in His life and death; as the Father sent Christ into the world, so Jesus is sending His disciples into the world (17:18). The mission is always to bear witness to the reality of the truth—the gospel of Jesus Christ in all its fulness. The truth makes it possible for guilty sinners to be declared holy and be used by God for His sacred purposes. Those who rightly respond to the truth are to worship in Spirit and truth (4:23) and witness to the truth in the power of the Spirit (15:26, 27). John the Baptist and John the Gospel author exemplify this witness to the truth (5:32, 33; 10:41; 19:35; 21:24). Jesus modeled this testimony in His confession before Pilate. Pilate’s cynical question about the definition of truth is a climactic mirror for John’s Gospel. Pilate was speaking to the truth standing right in front of him—and yet he refused to see truth. By contrast, the overarching purpose of John’s Gospel is to present the crucified Jesus as the Messiah and the Son of God, affirming that faith in Him is not only the means to eternal life but also the right response to the truth (20:31).

About the Contributors

Mark L. Bailey

Dr. Bailey assumed the role of DTS Chancellor after serving for 19 years as the Seminary’s fifth President, and continues his role as Sr. Professor in the Bible Exposition department. In addition to his years at Dallas Theological Seminary, he has pastored various churches in Arizona and Texas. He was a seminar instructor for Walk Thru the Bible Ministries for twenty years and is in demand for Bible conferences and other preaching engagements all over the country and world. His overseas ministries have included Venezuela, Argentina, Hungary, and China. He is also a regular tour leader in Israel, Jordan, Egypt, Turkey, Greece, and Rome. His board service includes Bible Study Fellowship, Walk Thru the Bible Ministries, and Word of Life.