For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Shantkumar S. Kunjam
Yes, it is true that God hates lying which is demonstrated in Acts 5:1-11 in the deaths of Ananias and his wife, and, as the Bible says, "it is impossible for God to lie" (Heb. 6:18). Our Lord has also said that devil is "a liar and the father of it" (Jn. 8:44). Also it is repeatedly said that no liar will enter the New Jerusalem (Rev. 21:8, 27 and 22:15).
So the question is why God has condoned lie specially in the O.T.?
This is not very easy to answer. Many godly people lied and also some people whose lying actions were accepted without criticism for the benefit of God's people. Even lying of an evil spirit is used by God to misguide a king (2 Chr. 18:18-21).
First let us remind ourselves with who God is. According to the Bible it is concluded that in His constitution God is Triune, Spirit and a Personality. In His ability God is omnipotent, omnipresent and omniscient. And in His character God is holy, love and light. Moreover, nothing happens without God's doing yet it is a fact that God is committed to the freedom of humans, of other creatures and of natural laws.
In all these things we also need to remind ourselves that God has a definite purpose "So that God may be all in all" (1 Cor. 15:28). With this purpose in focus God is doing two things: 1. "that in the dispensation of the fullness of the times He might gather together in one all things in Christ, both which are in heaven and which are on earth - in Him" (Eph. 1:10). 2. "For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them" (Eph. 2:10). So the history between Gen. 2:4 to Rev. 22:21, including our history is a history of God preparing a new humanity in Jesus Christ "to the praise of the glory of His grace" (Eph. 1:6). And in this new humanity God is forming a Bride for His Son.
So considering all these things the whole history, whether biblical or secular, is the history of God bringing His plan to conclusion.
Now let us talk about our main question. During the biblical history of four thousand years God prepared the world and a people group of Israelite nation for the coming of His Son, our Lord Jesus Christ. In this preparation God both used and at times ignored the weaknesses of people. God assimilated many weak people into the fold of His people. In fact none of them had full revelation of God's character as is known to us in Jesus Christ. Many of them knew and experienced God but never to the extent as the disciples had and we have experienced in Jesus our Lord: "But blessed are your eyes for they see and your ears for the hear, for assured, I say to you that many prophets and righteous men desired to see what you see, and did not see it, and to hear what you hear, and did not hear it"" (Mt. 13:16-17). So God in His mercy had "passed over the sins" of those people, forgiving them in advance with the planning to make full payment of their redemption in His Son's death (Rom. 3:25-26).
So having said all this, I have still not been able to answer our main question, Why God condoned lying in the O.T.? We can only say that God in His righteous wisdom saw it fit to use even those lyings, like He still uses weak people like us for His purpose. So let us just rely on Him and praise Him that He loves us and uses us in spite of our many weaknesses. Praise the Lord.
Lou Tercero
I think that perhaps if we ask GOD in prayer to inspire us towards diplomacy it would be beneficial to both parties.