"Their webs shall not become garments, neither shall they cover themselves with their works: their works are works of iniquity, and the act of violence is in their hands. Their feet run to evil, and they make haste to shed innocent blood: their thoughts are thoughts of iniquity; wasting and destruction are in their paths. The way of peace they know not; and there is no judgment in their goings: they have made them crooked paths: whosoever goeth therein shall not know peace."
For a covering, the Israelites could have chosen the Spirit of the living God (Isaiah 30:1); but instead, they sought security in their evil ways. Each man did "that which was right in his own eyes (Judges 17:6)." The godless are prone to think that their actions and plans serve to protect and secure their interests; but "all things are naked and opened (Hebrews 4:13)" unto the eyes of God, and He will not bless evil.
Romans 3:15-17 follows closely the wording of verses 7 and 8. Paul seems to have been referencing these same verses in his summary of mankind's sinful and hopeless condition. Even though Israel saw times of spiritual revival, the people soon returned to disobedience. The shedding of innocent blood was all too common. Christ made reference to Israel's shedding of innocent blood when He said, "..Upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias...(Matthew 23:35)." According to II Kings 21:16, "Manasseh shed innocent blood very much, till he had filled Jerusalem from one end to another... ." When the nations surrounding Israel should have seen godliness in Israel's wake, they saw destruction, misery and oppression. When Paul used these passages, he applied them to all of mankind. Isaiah is speaking directly to Israel; however, all of humanity is in the same wretched condition.
Even though Israel is not plagued currently with the same type of idolatry denounced by Isaiah, her spiritual condition is still miserable. She has a form of godliness, but she denies the power of it (II Timothy 3:5). Her rejection of Jesus' righteous authority has turned her out of the way of peace; and every proselyte of Judaism will not find the peace of God. Lasting peace comes only through faith in the Messiah's blood.