Yes, it is a sin to tell a lie. The ninth commandment found in Exodus 20:16 says, “You shall not bear false witness against your neighbor,” or, “You shall not lie.” Lying goes against the very nature of God. Scripture tells us God cannot lie; in fact, it is impossible for God to lie. (See Titus 1:2 and Hebrews 6:18.) The opposite of a lie is the truth. The Bible tells us that God is truth. Deuteronomy 32:4 says, “He is a rock, His work is perfect; for all His ways are justice, a God of truth and without injustice; righteous and upright is He.” God the Son, Jesus, said “I am the truth” in John 14:6. God the Holy Spirit is also called truth in 1 John 5:6, “...And it is the Spirit who bears witness because the Spirit is truth.” As Christians, we, also, are to be people of truth since we are now His children. How do we learn to be people of truth? By studying the truth, God’s Word, and the Bible. John 17:17 says, “Sanctify them by Your truth. Your Word is truth.” This verse tells us that God wants to set us apart by His truth and that the Bible is the truth by which He will do that. Therefore, it is a sin to lie because lying makes us look like the enemy; being a person of truth makes us look like the Lord.