Frankly, I don't understand it. We throw out the term, "grey issue" when it comes to lying but I think this is neither responsible nor biblical. God's thoughts on the truth are as black and white as they come.
"You shall not steal; you shall not deal falsely; you shall not lie to one another" (Leviticus 19:11).
"There are six things that the LORD hates, seven that are an abomination to him: haughty eyes, a lying tongue, and hands that shed innocent blood, a heart that devises wicked plans, feet that make haste to run to evil, a false witness who breathes out lies, and one who sows discord among brothers" (Proverbs 6:16-19).
"Keep your tongue from evil and your lips from speaking deceit" (Psalm 34:13).
"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)
People will accuse me of being too simplistic. But I think that this command is simple. God says do not lie, ever. There is not a single caveat in Scripture, nor ever any inclination that there are such things as planes of morality. Norman Geisler says that there is a hierarchy of values in the Bible and that, when some come into conflict, we need to subordinate the lower for the higher. So if mercy and truth-telling come into conflict, mercy wins out.
I disagree. God never, never says that lying is okay if (fill-in-the-blank). If we think that we need to disobey God to obey Him, we have a lack of trust in Him and a warped view of His law.
People will use the example of Rahab. You've probably heard it. "She lied to protect the Israelite spies she had hidden to keep safe and she's in the Hebrews 11 Hall of Faith," they will say. Rahab's lie comes in Joshua 2. If you read the account through, you'll see that the author of Joshua never condones or commends her lie. He simply states it, much like he states the fact that she was a prostitute. We are not arguing for the morality of prostitution because of this text. Why would we argue for lying? Furthermore, when she is mentioned in Hebrews 11:31, her lie is not what got her there; it is her reception of the spies and her belief in God.
In John 14:6 Jesus called Himself, "the truth." Numbers 23:19 says that God never lies. Psalm 119:160 says that all of God's words are truth. The Lord says in Zechariah 8:19, "Love truth." John 4:23 says that God requires us to worship Him in truth. First Corinthians 13:6 says that love is about the truth. Ephesians 6:14 calls us to put on the belt of truth. Second John 2:2 says that truth lives inside a Christian and will be with us forever.
The truth is not simplistic. It is a non-negotiable command for the Christian. We are called to it, no matter what. It is never okay to lie.