Since I also believe in free will, I have to accept the possibility.
I can't save the world. Jesus already did that. But in the Bible, Paul talks to the Colossians about "filling up what is lacking in the afflictions of Christ, on behalf of his body, which is the Church." Mark Shea explains it this way:
As to “lack”, the term doesn’t refer to God lacking anything, nor to some inadequacy on Christ’s part but to our lack. For instance, God is the giver of all things and intends us to have all we need. Yet, in this world, people experience lack everyday. Why? In no small part because we (who are entrusted with the task of distributing what is needed for the common good) don’t supply the lack. So people starve or go thirsty. Is that because there is a lack on the part of the author of Being? No.
In the same way, Christ’s sacrifice is sufficient. But since he has made us participants in that sacrifice, our acts of sacrifice *matter* too...
The bottom line is: Christ mediates his grace to us through creatures, especially other people.
So Scripture makes it clear that we are to participate in bringing the salvation of Christ to the world. But the whole world is saved not in one fell collective swoop, but one soul at a time. And for each soul, the moment of truth is the judgment that occurs at death.
I have a theory about this moment. I believe that, just as we cannot commit mortal sin without full knowledge of and consent to the sin, so we cannot be condemned to hell without similar requirements being met. So, at the moment of death, at some super-conscious level beyond the body, we will see everything. At that moment when our life passes before our eyes, we will see the full extent of our sins, and it will become clear how gloriously good and lovable is God. And that is what, at one time, tempted me to think that no one could go to Hell, for how could anyone come face to face with Love himself and not want to spend eternity there?
Since then, though, I have seen how pride and despair can distort a relationship. When confronted with our sins, we are apt either to get self-defensive or self-condemning. Either one, taken to the extreme, can cause us to reject reconciliation--and rebuff even Love himself. It's happened before.
Feel free to set me straight if I'm wrong. But I'd say it lines up pretty well with what St. Faustina writes in her diary:
God’s mercy sometimes touches the sinner at the last moment in a wondrous and mysterious way. Outwardly, it seems as if everything were lost, but it is not so. The soul, illumined by a ray of God’s powerful final grace, turns to God in the last moment with such a power of love that, in an instant, it receives from God absolution of sins and remission of punishment, while outwardly it shows no sign either of repentance or of contrition, because souls [at that stage] no longer react to external things. Oh, how beyond comprehension is God’s mercy! But - horror! - There are also souls who voluntarily and consciously reject and scorn this grace! Although a person is at the point of death, the merciful God gives the soul that interior vivid moment, so that if the soul is willing, it has the possibility of returning to God. But sometimes, the obduracy in souls is so great that consciously they choose hell...
St Faustina, whose visions gave us the Divine Mercy Chaplet and inspired the designation of the second Sunday of Easter as Divine Mercy Sunday, wrote about praying for those close to death. She related that Jesus said to her, "I desire that this mercy flow out upon the whole world through your heart. Let no one who approaches you go away without that trust in My mercy, which I so ardently desire for souls. Pray as much as you can for the dying. By your entreaties, obtain for them trust in My mercy, because they have most need of trust, and have it the least."
We are all, at that moment of truth, miserable sinners. Some of us will have formed in this world a habit of trusting God's grace; this will give us an advantage, in that we will be better primed to accept his mercy. But what about those who have no practice of turning to God? Those who are too smart for religion, are used to being in control of their lives, or have never been credibly evangelized? What about those who are all too aware of their sins, who don't think God will or can or should forgive them?
Jesus prayed on the cross for mercy for the people who killed him, and that day a thief and a pagan soldier became believers. Though it is improbable that I will imitate Jesus in his death, I can imitate Him in prayer. Maybe, by praying for those who will die today, I can unleash the grace that is waiting for them.
What if I did this every day?
What if you joined me?