There's a tradition in Christendom which says that faith in Jesus Christ as one's savior, and commitment to him as lord, is necessary for salvation. (Different Christian traditions might state this requirement differently; the important point is that almost everybody who hasn't been in contact with Christian missionaries, or isn't part of a chain which goes back to Christian missionaries, will fail to meet this requirement.)
There's another Christian tradition which says that one must have this faith before one's death.
While I see somewhat strong scriptural merit behind the first tradition (despite a growing number of Christian philosophers rejecting it; I think they're called inclusivists), I don't see much scriptural merit behind the second tradition. Furthermore, as my friend Patrick Todd pointed out to me at the Pacific SCP, it seems arbitrary for God to pick death as the moment beyond which there is no return. From the standpoint of eternity, why then? What's so important about that point? It seems that a less arbitrary point would be when a person has shaped his character in such a way that he would never have the faith which I described in the first paragraph of this post (this shaping might happen via what Robert Kane calls "self-forming actions"). A picture of how all this might happen is illustrated beautifully in C.S. Lewis' The Great Divorce. Furthermore, I bet that inclusivists might be more open to exclusivism if they rejected the second tradition.
So, I don't see much scriptural merit behind the second tradition. On the more philosophical side (and hence, more germane to this blog), it seems that death would be an arbitrary point at which to judge people's eternal destiny.