The Prophecies Of Isaiah
This is happening because, "For the Lord has a day of vengeance, a year of retribution, to uphold Zion's cause." (Isaiah 34:8) The Lord must judge the enemies of Zion because the people of Zion are His. He is going to keep the promise made to Abraham and his descendants, "I will bless those who bless you, and whoever curses you I will curse." (Genesis 12:3a)
"Edom's streams will be turned into pitch, her dust into burning sulfur; her land will become blazing pitch! It will not be quenched night or day; its smoke will rise forever. From generation to generation it will lie desolate; no one will ever pass through it again." (Isaiah 34:10) We have to keep in mind that Isaiah is speaking of the judgment of the end times, when the Lord suppresses all rebellion, and that He is using the word "Edom" to represent all those who have hated Him and His people. The Apostle John foretold the day of vengeance and the downfall of the corrupt world system of the end times in Revelation 18, in which he said that the Babylon of the last days would be burned by fire and never again inhabited. Edom in the Old Testament and Babylon in the New Testament are both used to represent rebellion against God, spiritual and moral corruption, pride and deception, and materialism. These things that are in opposition to God will be consumed as thoroughly as a sacrifice upon which God sends down fire from heaven. In the kingdom of Christ these attitudes will not be found.
It's not enjoyable to study the fearful judgment of the God who is a consuming fire, but I think it's important to note that these prophecies were given to the people of Israel to comfort them. The Lord is giving them these words in a time of distress. God wants them to know that He will judge their enemies. Abraham was called a friend of God and the Lord will act against the enemies of His friend. The people are able to take heart in knowing God will fight against those who have fought against them.
David, in a time of distress, called upon God to fight for him, "Contend, Lord, with those who contend with me; fight against those who fight against me. Take up shield and armor; arise and come to my aid. Brandish spear and javelin against those who pursue me. Say to me, 'I am your salvation.'" (Psalm 35:1-3) When someone hurts us terribly, without cause, we feel as David felt. We want to say as David said, "Lord, You have seen this: do not be silent. Do not be far from me, Lord. Awake, and rise to my defense! Contend for me, my God and Lord. Vindicate me in Your righteousness, Lord my God; do not let them gloat over me." (Psalm 35:22-25) The Lord will reassure His people in Isaiah 49 with words similar to those of David, "I will contend with those who contend with you, and your children I will save." (v 25b)
Terrible as the thought of judgment is, the Lord is giving this prophecy to an oppressed and fearful people who need a word of hope. They need to know God has seen their affliction and that it won't go unpunished. He has a day of reckoning in store for the cruel enemy. He is righteous and will not turn a blind eye against sin or simply shake His head and shrug His shoulders at the injustices of this fallen world. As children of God, we have a Father who is responsible for us. This is why He says, "It is Mine to avenge; I will repay." (Deuteronomy 32:35) Like a parent watching over a small and helpless child, it is God's duty to avenge us and repay our enemies.