The LORD is the God of Israel and, therefore, Israel can walk in His paths with holiness and righteousness because His holiness is with them and on them.
From mountain to mountain, from meal to meal the LORD God points us to His banquet, already prepared; the marriage feast of the Lamb in His Kingdom which shall have no end!
Isaiah first reminds the people of who they are and then tells them why they are who they are; to bring the teachings and promises of the LORD to all people.