Psalm 46 was the inspiration for Martin Luther’s hymn, “A Mighty Fortress Is Our God.”
46:1 [testimony of the psalmist] God [“God alone is our all in all” (Spurgeon)] is our  refuge [shelter; stresses the defensive aspect of God’s assistance; a place of protection and absolute safety] and  strength [stresses the offensive aspect of God’s assistance; to hold up or empower the weak for action], an ever-present [abundantly found; accessible in times of need and enough or sufficient to handle any situation; cf. Heb. 4:16]  help in trouble [of all kinds].
46:2 Therefore [because of 46:1; we can face the future with confidence when we remember God’s help in the past] we will not fear [we are not exempt from troubles, but because of God’s strength we can face troubles without fear; fear is a natural response to natural disasters; this kind of fear reflects lack of confidence in God], [description of powerful forces which mankind cannot control; symbolize the worst of troubles] though [regardless of the kind of trouble; even when seemingly immovable things are moved] the earth give way and the mountains fall into the heart of the sea,
46:3 though its waters roar and foam and the mountains quake with their surging [46:2-3 emphasize the worst that could happen; perhaps the result of a major earthquake].
46:4 [contrast the calm setting of these verses with the tumultuous setting of the previous verses] There is a river [“a life-giving sign of God’s presence among His people” (Dean); symbolizes God’s provision for His people] whose streams [reminder that water is essential to life] make glad [by giving assurance of God’s provision] the city of God [Jerusalem], the holy place [temple] where the Most High [Heb. Elyon] dwells [abides].
46:5 God is within [sure and near; God’s presence eliminates the need for fear] her [Jerusalem], she will not fall [moved, shaken]; God will help her [refers to stability] at break of day [when darkness turns to light; ancient armies often launched their attacks just before dawn; a vulnerable time].
46:6 Nations are in uproar [suggests evil people/forces were attacking the city of God; perhaps a reference to an event in history when Jerusalem was under attack], kingdoms fall; he lifts his voice [speaks a word; His voice is mighty], the earth melts [reminder that God is in control of all the earth and everything in it].
46:7 [cf. 46:11] The LORD Almighty [or Lord of Hosts: pictures God as commander of heavenly armies and Israel’s earthly armies] is with us [not distant or aloof; actively involved in human events; basis for assurance; cf. Matt. 1:23]; the God of Jacob [Jacob’s name changed to Israel (Gen. 32:28)] is our fortress [stronghold against an enemy; implies inaccessible height: “our high stronghold”].
46:8 Come and see [envision] the works [the evidence; “all the acts of God in the history of salvation: the exodus, the conquest, the period of the judges, and the monarchy” (Dean); evidence of His care, protection, providential rule] of the LORD, the desolations [God’s judgments in history] he has brought on the earth.
46:9 [God’s power over human history] He makes wars cease to the ends of the earth; he breaks the [instruments of warfare] bow and shatters the spear, he burns the shields with fire.
46:10 “Be still [cease striving; let your hands drop; relax; depend completely on God], and know [being still precedes knowing; intimate knowledge that comes through personal experience; admit, realize, acknowledge] that I am God; I will be exalted [extolled, praised, lifted up] among the nations, I will be exalted in the earth.”
Note: For more on what it means to “be still” read my devotional notes on this verse.
46:11 [cf. 46:7] The LORD Almighty is with us; the God of Jacob [God had to teach Jacob the lesson of 46:10] is our fortress [see comments on 46:7].