3 The forgiveness of “sins” (ʿāwōn, GK 6411, lit., “guilt”) is God’s gracious act of removing the consequences of sin as well as the sin itself (cf. 32:1; 51:2; 90:8). It is synonymous with “heals all your diseases.” The “diseases” may be forms of sickness (cf. Mk 2:7); but more likely it is a metaphor for adversities or setbacks (cf. Dt 29:22; Jer 14:19; 16:4), similar to punishment (“sins”). For “healing” as an act of restoration, see 147:3 and Jeremiah 30:12–17; 51:8–9.
forgiveness (v. 3) He first mentions the forgiveness of sins—not just some of his iniquities! What good would that be when one sin is sufficient enough to condemn before a holy God. The forgiveness of God covers ‘all’ iniquities. And the forgiveness of iniquities—let us never forget—flows from God through the channel of the redeeming work of Jesus Christ.
healing (v. 3) David moves to the next blessing: God’s healing of diseases. Henry T. Mahan writes: ‘The diseases of this body are the results of sin and God will heal them when it is according to his will and when it serves his purpose, but the diseases referred to here are spiritual diseases, which, like our sins, are all healed in Christ. He bore all our spiritual sicknesses and diseases in his body on the tree and by his sufferings we are healed for ever.…’
103:3 But above all else, we should be thankful to Him for forgiving all our iniquities. It is an unspeakable miracle of divine grace that crimson sins can be made whiter than snow. I can empathize with the man who chose one word for his tombstone—FORGIVEN. And also with the Irishman who said, “The Lord Jesus has forgiven me all my sins, and He’s never going to hear the end of it.” To know that our sins have been put away forever by the precious blood of Christ—well, it’s just too much to take in. The second benefit to be remembered is the healing of all our diseases. Before we get into the problem that this raises, let us notice that healing comes after forgiveness. The physical is closely related to the spiritual. While not all sickness is a direct result of sin, some of it is. Where the connection exists, forgiveness must precede healing.
But the obvious problem is still there. The verse says “… who heals all your diseases.” Yet as a matter of practical experience we know that not all diseases are healed, that we will all die sooner or later if the Lord does not come in the meantime. So what does the verse mean? In seeking an answer, we would make the following observations.
First, all genuine healing is from God. If you have been sick, and then have recovered, you can thank God for your recovery because He is the source of all healing. One of the names of God in the Old Testament is Jehovah Rophi—the Lord your Healer. Every instance of true healing comes from Him.
Second, the Lord is able to heal all kinds of diseases. There is no such thing with Him as an incurable disease.
Third, the Lord can heal by the use of natural means over a period of time or He can heal miraculously and instantly. No limit can be placed on His power to heal.
Fourth, when He was on earth the Lord actually healed all that were brought to Him (Matt. 8:16).
Fifth, during the Millennium He will actually heal all diseases (Isa. 33:24; Jer. 30:17) except in the case of those who rebel against Him (Isa. 65:20b).
But whatever else the verse means, it cannot mean that the believer can claim healing for every disease, because in other verses of the Psalm we are reminded of the shortness of life and of the certainty of its coming to an end (see vv. 15, 16). What the verse says to me is that whenever a believer is healed, this is a mercy from God, and He should be acknowledged and thanked as the Healer.
103:3 diseases. This is not a promise, but rather a testimony which should be understood in the light of Dt 32:39.
103:3 Heals often refers to curing someone from a physical sickness, but it can also be used as a metaphor for restoring the moral and spiritual life (e.g., Isa. 6:10; 53:5; Jer. 3:22; Hos. 14:4). Since it is in parallel with forgives, the metaphorical use may be intended here. Thus iniquity is like diseases, which weaken and corrupt; it is God’s mercy that takes them away. These sentiments reflect David’s own experience of God’s forgiveness (cf. 2 Samuel 12; Psalm 51).
103:3 forgives all your iniquity. The primary benefit of grace is the forgiveness of sins (Acts 13:38). God is compassionate toward His repentant people.
 VanGemeren, W. A. (2008). Psalms. In T. Longman III & D. E. Garland (Eds.), The Expositor’s Bible Commentary: Psalms (Revised Edition) (Vol. 5, p. 757). Grand Rapids, MI: Zondervan.
 Ellsworth, R. (2006). Opening up Psalms (p. 133). Leominster: Day One Publications.
 MacDonald, W. (1995). Believer’s Bible Commentary: Old and New Testaments. (A. Farstad, Ed.) (pp. 703–704). Nashville: Thomas Nelson.
 MacArthur, J. F., Jr. (2006). The MacArthur study Bible: New American Standard Bible. (Ps 103:3). Nashville, TN: Thomas Nelson Publishers.
 Crossway Bibles. (2008). The ESV Study Bible (p. 1068). Wheaton, IL: Crossway Bibles.
 Sproul, R. C. (Ed.). (2005). The Reformation Study Bible: English Standard Version (p. 826). Orlando, FL; Lake Mary, FL: Ligonier Ministries.