One key to understanding the theology of Isaiah 42:1-4 is to highlight the contrast between God’s Servant (Isaiah 42:1) and the idols of the previous chapter.  Unlike the idols, God’s Servant will actually deliver.  That is because He is Spirit-driven or Spirit empowered (“I have put my Spirit upon him”).  Then the rest of verse 1 through verse 4 describe what He will do and how He will do it.  The structure is very simple.  The theology is conveyed through the description and is designed to bolster our faith in God alone, rather than choosing to worship all our American idols.  Isaiah 42:3 describes how our Savior deals with us in our weakness.  On the cross Jesus experienced total weakness-to-the-point-of-death so that He could share God’s strength with us.  Philippians 2:7-8 describe Jesus like Isaiah did (“servant”).  Our Savior will bring justice only because He suffered the wrath of God for our sins.  Because He did that for us, instead of justice, we received mercy so we can now administer justice and mercy to those in need.