James Montgomery Boice in his comments on this verse (Psalm 46:10) writes, “Therefore, in this setting, ‘Be still, and know that I am God’ is not advice to us to lead a contemplative life….It means rather, ‘Lay down your arms. Surrender, and acknowledge that I am the one and only victorious God.’”
There is a dual aspect to “Be still, and know that I am God.” To the Lord’s enemies it is a sure threat that your arms will be destroyed for he brings desolation – breaking the bow, shattering the spear, and burning the chariots. You, O man, will be brought low and the Lord of hosts will be exalted among the nations, he will be exalted in the earth.
Yet those whom he has covenanted with, Jacob his chosen heritage, lay down their arms now while it is called “today.” They stand still and see the salvation of the Lord in all that God is for them in the Person and work of Jesus Christ. Among these, God’s name is hallowed to ends of the earth. In this way also he is exalted among the nations. Christ, as their King, subdues them to himself, he rules and defends them, and he restrains and conquers both his and their enemies.