Atonement and propitiation.

Lets think about the atoning sacrifice for a second. If it is true that Christ died for all men, then Christ's sacrifice, doesn't save anyone at all, it simply is not able to by the demonstration that people who Christ died for are in Hell as well as heaven. Atonement means the remission of sins, and the reconciliation of man to God. Thats what Christ's sacrifice did. Remission is the cancelation of a debt, so we are not sinful anymore, and the reconciliation part is the reunion or bringing together. Does Christ actually do this for all men? Is it possible that this is true... I Don't think Christ did this for all men, just by implication. 

On to propitiation.

In Christian theology, propitiation is the work of Jesus Christ on the cross, by which He fulfills the wrath of God (both an emotional response of anger and a moral response of indignation), and conciliates Him who would otherwise be offended by our sin and would demand that we pay the penalty for it. The concept of propitiation is associated in some Christian theological systems with indemnity, imputed righteousness, and substitutionary atonement.

So in 1 John 2:2 
He is the propitiation for our sins, and not for ours only but also for the sins of the whole world. 
And Again
1 John 4:10
In this is love, not that we have loved God but that he loved us and sent his Son to be the propitiation for our sins.

Can we really conclude that Christ is the propitiation for the whole world? Christ's death imputed righteousness onto us, we are no longer sinful in Gods eyes. So we are thus left with two options, either universalism, or Gods sovereign choice in who to save or who to not save.
Perhaps the speaker, John, is talking to the Jews and telling them that they are no longer the only ones chosen for salvation but also the gentiles, or maybe it is the spanning of salvation into different countries and cultures. 
I think Mathew Henry says it well:
not only for the past, or us present believers, but for the sins of all who shall hereafter believe on him or come to God through him. The extent and intent of the Mediator's death reach to all tribes, nations, and countries. As he is the only, so he is the universal atonement and propitiation for all that are saved and brought home to God, and to his favour and forgiveness.

Taking into Account the speaker is John, he has made it very clear in John 6:39; 17:9-10, that only those the the Father gives Him are Christ's.