The Bible classifies lying as something immoral and sinful. "Lying lips are an abomination to the Lord" (Proverbs 12:22), and "lying lips" and "a deceitful tongue" are things from which deliverance is sought (Psalm 120:2). A mouth that speaks truth "endures forever" while a mouth that tells lies "is but for a moment" (Proverbs 12:19). Those whose hearts are full of lying words are associated with things like oppression, transgression, and denial of God (Isaiah 59:13). The prophet Hosea calls lying (along with murder, thievery, and adultery) a thing that "breaks all bounds" and results in bloodshed (Hosea 4:2). So, can God lie?
Can God lie?
The Apostle Paul promised the recipients of his letters by appealing to God's truthfulness. He said "I am speaking the truth in Christ—I am not lying; my conscience bears me witness in the Holy Spirit" (Romans 9:1) and "The God and Father of the Lord Jesus, he who is blessed forever, knows that I am not lying" (2 Corinthians 11:31). Clearly, Paul believed God's character to be honest, true, and truthful. God was the standard he appealed to. He wanted God to look at his words and judge them honest. It would not make much sense for Paul to do this unless God was characterized as an inherently truthful person.
We know that God is the only one who is purely good (Luke 18:19). He is also wise (Romans 16:27) and perfect. "The Rock, his work is perfect, for all his ways are justice. A God of faithfulness and without iniquity, just and upright is he" (Deuteronomy 32:4). "This God—his way is perfect; the word of the Lord proves true; he is a shield for all those who take refuge in him" (Psalm 18:30; 2 Samuel 22:31). Look at that list of character traits: God does perfect work. All His ways are just. He is a God of faithfulness. He is without sin. He is just and upright. He is perfect. His Word proves true. He protects those who trust Him. Since God's character is a truthful character, it is irrational to think that God can lie.
Furthermore, God tells us plainly that He does not lie. "God is not man, that he should lie, or a son of man, that he should change his mind. Has he said, and will he not do it? Or has he spoken, and will he not fulfill it?" (Numbers 23:19). The Bible is God's inspired Word (2 Timothy 3:16). That word proves true (Psalm 18:30). And that word tells us that God does not lie (Numbers 23:19).
But wait! If God is omnipotent, how could there be anything that He cannot do? The question is not whether or not God has the power to lie, the question is whether or not He wants to lie. There are many terrible things that we all have it within our power to do, but we are revolted by the idea of doing them. If, for example, a mother was asked to willingly harm her child, she might respond by saying, "no, I could never do that!" She is not saying "I don't have the power to do that;" she is saying "that goes completely against my will, my desires, and my character." It is the same with God, and committing sin. And in that way, God cannot lie, because it goes completely against who He is.
The attributes of God, what are they?
Is God immutable? What is the significance of the immutability of God?
Does God change His mind?
Is there anything God cannot do?
What does it mean that God forgets our sin? Does He forget?
Truth about God