WHAT IS A LIE?

Intro.
1. It is our duty to speak the truth - Eph. 4:25 (Zech. 8:16-17)
  a. From pure motives (8:16-17)
  b. God hates a lying tongue - Prov. 6:16-17
2. Lying is part of the old man of sin - Col. 3:9
3. Liars will lose their souls - Rev. 21:8; 22:15
4. Dishonesty takes the form of words and/or deeds.

I. A LIE IS:
1. "An intentional violation of the truth." (Easton's Dictionary)   -Dishonesty-
2. Deceit (with the tongue) - cf. Psa. 5:6; 101:7; Prov. 12:22 (19:9)
3. Proceeds from a dishonest heart - Mk. 7:21-22

II. "If the words you use are "technically" true but designed to imply an untruth, is it still a lie?"
1. Yes. Lie: "To create a false or misleading impression." (Merriam-Webster)
2. 1 Tim. 1:10 - Perjurers ("false swearer").
3. cf. Abraham and Sarah - Gen. 20:1-2, 3, 11-13. The implication was clear - and false.
4. cf. Isa. 28:15 - When we hide ourselves under falsehood, disguised as truth, we are being dishonest and following the course of Satan - cf. 2 Cor. 11:13-15

III. "What if it is for a good cause?"
1. "A good cause?" - Rom. 3:8
-cf. Abraham and Sarah - Gen. 20:11-13
2. Self-defined righteousness! (Jer. 10:23)
3. If a cause (or situation) is based on a lie, how then can it be seen as "good"? (Only from the standpoint of human wisdom, not God's wisdom.)

IV. "Is there a difference if the person the lie is told to is a Christian or a sinner?"
  -No such distinction is made in scriptures between what is a lie and what is not - cf. 1 Pet. 3:10; Matt. 5:37 (cf. Jno. 8:44)

V. "What if the lie is to make an unfair system or situation work out right for you, is it then justified?"
1. Again, Abraham & Sarah are an example of this (Gen. 20)
  a. "Shall we do evil that good may come?" (Rom. 3:8; 6:1-2)
  b. Col. 3:17 - Whatsoever you do….all in the name of the Lord
2. Such a view will put one into a position of justifying sin (cf. the "white lie").
3. Accept the consequences that come from speaking truthfully - 1 Pet. 4:14-16 (cf. Matt. 26:61-65; Jno. 18:36-37).

Conclusion
     The truthful lip will be established forever - Prov. 12:19