These are the identical words that Nehemiah had used in his prayer when he first heard from his brother that the walls of Jerusalem were still broken down (Nehemiah 1:5). This was a title for God borrowed from Deuteronomy 7:21, a chapter that highlighted how the Lord in mercy adopted a weak and insignificant people to be his treasured possession and then prospered them. In that context Moses had specifically said, You shall not be in dread of [your enemies], for the Lord your God is in your midst, a great and awesome God
(Deuteronomy 7:21), as Israel’s history has subsequently demonstrated. Nehemiah wants his demoralized people to join him in thinking big of their God.
14 And I looked and arose and said to the nobles and to the officials and to the rest of the people, “Do not be afraid of them. Remember the Lord, who is great and awesome, and fight for your brothers, your sons, your daughters, your wives, and your homes.”