The eternal God is holy (Isaiah 6:3). His holiness makes it impossible for Him to lie, for by “holy” is meant that God is absolute, transcendent purity. He does not conform to the standard; He is the standard. As Tozer has said, “He is absolutely holy with an infinite, incomprehensible fullness of purity that is incapable of being other than it is” (The Knowledge of the Holy, p. 105). Since God is holy, all His other characteristics or attributes are also holy. Thus, when God speaks, He will not and cannot lie. He never deceives; neither does He distort or misrepresent what He says or does. Lying is against His nature.
This means that God’s Word, the Bible, is completely trustworthy (1 Kings 8:56; Psalm 119:160). Hebrews 6:13–14 says that the basis of God’s promise to Abraham was God’s own unchanging nature: “Since there was no one greater for him to swear by, he swore by himself, saying, ‘I will surely bless you and give you many descendants.’ ” The text continues in Hebrews 6:17–18, “Because God wanted to make the unchanging nature of his purpose very clear to the heirs of what was promised, he confirmed it with an oath.… It is impossible for God to lie.”
Two things are revealed here about God’s truthfulness. First, He stands on His own Word, the oath He made to Himself. Since He is the holy God, it is impossible for Him to lie. He cannot contradict His own pure character. Second, God has kept the promise He made to Abraham in Genesis 12:1–3, that through Abraham’s Seed the world would be blessed. That promise came true some 2,000 years later when Jesus Christ came into the world (Galatians 3:16). Jesus was of the Seed of Abraham and is now the Savior of the world through His death, burial, and resurrection. Those who place their faith in Jesus Christ receive His forgiveness and eternal life (John 1:12; 3:16). The promise to Abraham, then, continues to be carried out through the person of risen Christ. This means the promise is still in effect today and will be throughout eternity, for Jesus Christ is the Fulfiller of the promise (see 2 Corinthians 1:20).
If God could lie, He would not be the eternal, personal God revealed in the Bible through Jesus Christ. Furthermore, who wants to place their faith in a God who cannot be trusted in what He says? If God could lie, He would have something in common with Satan, the father of lies (John 8:44), and that would be impossible. If God could lie, He would be just like us—humans sometimes lie, misrepresent or distort the truth. But “God is not a man, that he should lie, nor a son of man, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill?” (Numbers 23:19).
The biblical God is a God of pure moral health. He wants us to experience that same moral health through faith in Jesus Christ so we can live a life transformed by His power. May we give evidence of His holiness in our daily lives (1 Peter 1:15–16). May we love the truth as God does.
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.