In this song of deep distress, the worship leader, aware that some of God's people experience particularly intense trials, leads them to the only sure help. He first leads them through words of complaint, words that may well express their own feelings. Then, he leads them to close with an expression of triumph in the One Who can and does help.
The problem is truly intense - the song expresses the fearful thought that it may even be the Lord Himself Who is angry. With that possibility, the worshipper is led to cry out for mercy, to pour out all his fears, and to wail out that his body, soul, and spirit can't take much more of this trial - that he might actually be headed for an early grave! In such a circumstance he's forced to cry out to the Lord, "But You, O Lord - how long?" In other words, "Lord, how long are You going to ignore me? I'm DYING! Will You receive praise from me if I lie in the grave? I can't cry any harder! O deliver me!"
But then, remembering how great is the mercy of the God to Whom he prays, remembering that He is the Covenant God of Israel, remembering that His covenant mercies are forever to them that fear Him, the worshipper comes to realize that the Lord does indeed hear him. But, realizing the meaning of such a thought, his joy in the sureness of God's salvation is almost more than his fear and sorrow were previously. He turns toward all his enemies, and, almost shouting at them, he says, "Depart from me, all you workers of iniquity; for the Lord HAS HEARD my supplication!"
Do you sometimes have needs so deep and so intense that you don't know what to do? Relief may be much nearer than you imagine. Do as the song leader did, and express your pain truthfully and in detail to a merciful God. Sing this song to Him. Realize Who it is to Whom you cry. Realize that your Lord went through the deepest, most sorrowful experience of all - for YOU - and that He can and will therefore care for you. Then turn to Satan your enemy, and shout at him that your God has heard you!