What does it mean that it is impossible for God to lie (Hebrews 6:18)?

Answer  
  

Hebrews 6:18 builds upon preceding verses by affirming, “So God has given both his promise and his oath. These two things are unchangeable because it is impossible for God to lie. Therefore, we who have fled to him for refuge can have great confidence as we hold to the hope that lies before us” (NLT). The broader context of this discussion revolves around [God’s promises](promises-of-God.html), exemplified through Abraham. Verse 13 underscores how God solidified His promise to Abraham by taking an oath with His name, and He did this to “make the unchanging nature of His purpose very clear.” We can trust in His promises because of His steadfastness. It is impossible for God to lie.  
  

God’s truthfulness is tied to His holiness, a trait characterizing His absolute moral perfection. His holiness also embodies integrity, defined as “unwavering adherence to moral principles.” However, God does not conform to any moral standard; He *is* the ultimate standard. Due to God’s absolute goodness and complete separation from all forms of evil (including lying), we know His Word is truthful (see John 17:17\).  
  

The entire letter to the Hebrews aims to admonish, challenge, and uplift persecuted believers, particularly Jewish converts who might have been tempted to apostatize. Hebrews 6:18 serves as a source of encouragement, as it is God’s unwavering truthfulness and immutability that offer hope. That hope is called “an anchor for the soul, firm and secure” (verse 19\). If God were to deceive us about His actions through Jesus, we would have no hope, no anchor. Hence, our confidence in God rests upon His unchanging nature.  
  

Faith is only as valid as its object. As Timothy Keller stressed, “It is not the strength of your faith but the object of your faith that actually saves you. Strong faith in a weak branch is fatally inferior to weak faith in a strong branch” (*The Reason for God*, Penguin Books, 2009, p. 244\). We can have faith in God because it is impossible for Him to lie.  
  

Consider two aircraft, one in good mechanical condition, and the other with a faulty engine. A person will reach his or her destination in the reliable aircraft regardless of the amount of faith he or she has. Even weak faith in the reliable plane is enough to reach the destination safely. Conversely, even strong faith in the faulty craft will not compensate for the plane’s broken condition. It’s not the *faith* that gets us to our destination, but the *vehicle* we are in. So it is with our salvation. It’s not the strength of our faith that saves us but the strength of our Savior. He is the Truth (John 14:6\), and it is impossible for Him to lie.  
  

Several other passages affirm God’s immutability and truthfulness. An example is Numbers 23:19, “God is not human, that he should lie, not a human being, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill?" The apostle James also asserts that God “does not change like shifting shadows” (James 1:17\).  
  

Because it is impossible for God to lie, we can have confidence in the gospel message. We know that, when God declares us forgiven and righteous, He can be trusted. We are welcomed into His kingdom and reconciled to Him because His word is absolute. This confidence permeates our lifestyle, motivating us to live for God. It also produces hope within us and resilience in the face of adversity. In moments of doubt, it is a valuable practice to reflect on God’s unchanging attributes, as revealed in Scripture.  
  

