Again you are just parroting Calvin's line.
Christ died for the sins of the world, as that passage clearly teaches.
Those who believe him are not condemned. Nothing is said about sheep.
Those who do not believe in him are condemned. Nothing is said about goats.
It is interesting to note that in all the Bible the only contrast between sheep and goats is in the judgment of the nations, a judgment of gentiles that takes place between the Tribulation and the Millennial Kingdom well after the saints have been raptured.
It also may be noted that "sheep" are referred to as the "unsaved" in Isa.53:6, a verse often used to refer to the depravity of man.
Also in that very same verse: "The Lord hath laid on Him the iniquity of us ALL."
This is so very typical of John, and one that took me a bit of time to work through.
It is something that I consider most of determined Calvinistic thinkers would probably reject because there is a bit of reluctance of any who adopt some scheme to modify that view. So, I am at times considered a stranger in that camp - though I readily accept the doctrines of grace.
This is my opinion:
John used "world" in two ways, One was as an expression apparently typical of the exaggerations of the ancients (in our day it is referred to as "evangelistic-ally speaking." One Scripture - John 12:19 "the whole world has gone after Him," or as the NASB says, "everyone has gone after him!" It is evident this was an expression used in excited times or exasperation.
The other is when John uses the word "world" in such places as 3:16, I do not look at it as exageration or exuberant reaction, but a statement of fact.
So, my "calvinism" is somewhat modified on this point, which is why the propitiation and unbelief are so much more important.
When the lost face the final judgment and realize that the ONLY item standing between them and heaven is "unbelief" what a great judgment recompense that will be. The recognition that the propitiation was accepted by God, and yet that person did not believe, then they have to dwell forever knowing what they missed, what could have been but can never be, is far greater than one merely punished for their sins. This punishment is eternal, when everyone knows the Scriptures often present the picture of wrong done receives a temporary judgment and then restitution.
Are folks in hell because of sin(s)? No Doubt. All have sinned.
What separates the believer from the unbeliever, the final estate of heaven rather then hell? Belief.
I am in no way diminishing the sins of humankind, nor the punishment of hell, by accepting that John stated that the propitiation was not only for the believer but for the whole world in the literal meaning.