Good Bible study requires solid OBSERVATION skills. Let the Bible speak and it will make itself clear and understandable! Calvinists and many others fight over the passage because of faulty preconceptions. The passage is not saying, as some Calvinists charge, that God has already "saved" the entire world. Some think that the passage can be interpreted as universalism if one does not believe in the hard-core Calvinistic doctrine of Limited Atonement. That is, that Christ died only for the elect. I have studied thoroughly their faulty view of Limited Atonement, and it won't fly doctrinally! This passage is arguing that Christ died for the sins of the world but the world, that is each individual, must appropriate and believe in His sacrifice. The provision is there but it must be accepted.
Some years ago I did a major study on this passage and on Limited Atonement. I found that many hard-core Calvinists may be misunderstood because they say what I say: "Christ's sacrifice is sufficient for the world but applied only to the elect." This is so because the doctrine of Total Depravity kicks in. No one by himself will come to Christ without the sovereign drawing of the Spirit and the calling of God. Read John 6:37, 39, 44.
Before reading the comments below, you need to first read the verses. On these verses, I believe the Scottish Calvinist C. K. Barrett and the great Presbyterian scholar Charles Hodge says it best. Barrett writes:
On "the world" the absence of the article has the effect of emphasizing the nature rather than the particularity of the object of the verb. … Since transgressions no longer [are] counted against men the way was open for reconciliation; nothing remained but for men to take it. This however they could not do unless they were informed of the possibility [of salvation] now open to them. This brings Paul back to verse 19b to the theme of his ministry. … We have the ministry, as Paul does, of the message of reconciliation.
Hodge says:
"God was in Christ" is a proof of His being engaged, so to speak, in the great work of reconciling the world unto Himself. ... This means God was making atonement for the sins of the world; He set Christ forth as a propitiation.
"To reconcile unto Himself" does not mean to convert, or [even] to render friendly to Himself. This reconciliation is said to be effected by the death of Christ as a sacrifice; and secondly, because what follows is not a proof of God's converting the world, but it is a proof of His being in Christ (i.e. in His death) is that He does not impute to men their trespasses, and that He has established the ministry of reconciliation. … The evidence that the death of Christ has been accepted as an expiation for sin, of infinite value and efficiency, is the fact that God has commissioned His ministers to announce to all men that God is reconciled and ready to forgive, so that whosoever will my turn unto Him and live.
"To reconcile unto Himself" does not mean to convert, or [even] to render friendly to Himself. This reconciliation is said to be effected by the death of Christ as a sacrifice; and secondly, because what follows is not a proof of God's converting the world, but it is a proof of His being in Christ (i.e. in His death) is that He does not impute to men their trespasses, and that He has established the ministry of reconciliation. … The evidence that the death of Christ has been accepted as an expiation for sin, of infinite value and efficiency, is the fact that God has commissioned His ministers to announce to all men that God is reconciled and ready to forgive, so that whosoever will my turn unto Him and live.
Christ made peace possible (Eph. 2:11-19). No longer need people be the objects of God wrath (Rom. 5:9). By trusting themselves to the reconciling work of Christ alone, people pass from God's wrath to God's blessing (Acts 16:30-31; Rom. 8:1).
I hope this helps. I believe these are good explanations where in the past confusion has reigned!
–Dr. Mal Couch