The psalmist, having taught his people to look back with joy and praise on what God had done for him and them, here teaches them to look forward with faith, and hope, and prayer, upon what God would further do for them: The king rejoices in God (Ps. 21:1), and therefore we will be thankful; the king trusteth in God (21:7), therefore will we be encouraged. The joy and confidence of Christ our King is the ground of all our joy and confidence.
I. They are confident of the stability of David’s kingdom. Through the mercy of the Most High, and not through his own merit or strength, he shall not be moved. His prosperous state shall not be disturbed; his faith and hope in God, which are the stay of his spirit, shall not be shaken. The mercy of the Most High (the divine goodness, power, and dominion) is enough to secure our happiness, and therefore our trust in that mercy should be enough to silence all our fears. God being at Christ’s right hand in his sufferings (Ps. 16:8) and he being at God’s right hand in his glory, we may be sure he shall not, he cannot, be moved, but continues ever.
II. They are confident of the destruction of all the impenitent implacable enemies of David’s kingdom. The success with which God had blessed David’s arms hitherto was an earnest of the rest which God would give him from all his enemies round about, and a type of the total overthrow of all Christ’s enemies who would not have him to reign over them. Observe, 1. The description of his enemies. They are such as hate him, Ps. 21:8. They hated David because God had set him apart for himself, hated Christ because they hated the light; but both were hated without any just cause, and in both God was hated, Jn. 15:23, Jn. 15:25. 2. The designs of his enemies (Ps. 21:11): They intended evil against thee, and imagined a mischievous device; they pretended to fight against David only, but their enmity was against God himself. Those that aimed to un-king David aimed, in effect, to un-God Jehovah. What is devised and designed against religion, and against the instruments God raises up to support and advance it, is very evil and mischievous, and God takes it as devised and designed against himself and will so reckon for it. (3.) The disappointment of them: “They devise what they are not able to perform,” Ps. 21:11. Their malice is impotent, and they imagine a vain thing, Ps. 2:1. (4.) The discovery of them (Ps. 21:8): “Thy hand shall find them out. Though ever so artfully disguised by the pretences and professions of friendship, though mingled with the faithful subjects of this kingdom and hardly to be distinguished from them, though flying from justice and absconding in their close places, yet thy hand shall find them out wherever they are.” There is no escaping God’s avenging eye, no going out of the reach of his hand; rocks and mountains will be no better shelter at last than fig-leaves were at first. (5.) The destruction of them; it will be an utter destruction (Lk 19:27); they shall be swallowed up and devoured, Ps. 21:9. Hell, the portion of all Christ’s enemies, is the complete misery both of body and soul. Their fruit and their seed shall be destroyed, Ps. 21:10. The enemies of God’s kingdom, in every age, shall fall under the same doom, and the whole generation of them will at last be rooted out, and all opposing rule, principality, and power, shall be put down. The arrows of God’s wrath shall confound them and put them to flight, being levelled at the face of them, Ps. 21:12. That will be the lot of daring enemies that face God. The fire of God’s wrath will consume them (PS. 21:9); they shall not only be cast into a furnace of fire (Mt. 13:42), but he shall make them themselves as a fiery oven or furnace; they shall be their own tormentors; the reflections and terrors of their own consciences will be their hell. Those that might have had Christ to rule and save them, but rejected him and fought against him, shall find that even the remembrance of that will be enough to make them, to eternity, a fiery oven to themselves: it is the worm that dies not.
III. In this confidence they beg of God that he would still appear for his anointed (Ps. 21:13), that he would act for him in his own strength, by the immediate operations of his power as Lord of hosts and Father of spirits, making little use of means and instruments. And, 1. Hereby he would exalt himself and glorify his own name. “We have but little strength, and are not so active for thee as we should be, which is our shame; Lord, take the work into thy own hands, do it, without us, and it will be thy glory.” 2. Hereupon they would exalt him: “So will we sing, and praise thy power, the more triumphantly.” The less God has of our service when a deliverance is in the working the more he must have of our praises when it is wrought without us.