If Jesus' sacrifice was not retroactive, then He did not come to save the "whole world", as you believe, but only those who lived during His earthly life or after Him. Why do you think His sacrifice applies to you now, since you didn't exist back then, but it doesn't apply to those who came before Jesus within time? Consider these:
Matt 8:11 : I say to you that many will come from the east and the west, and will take their places at the feast with Abraham, Isaac and Jacob in the kingdom of heaven.
Luke 13:27-28 : 27 "But he will reply, 'I don't know you or where you come from. Away from me, all you evildoers!' 28 "There will be weeping there, and gnashing of teeth, when you see Abraham, Isaac and Jacob and all the prophets in the kingdom of God, but you yourselves thrown out.
So, are you saying that Jesus did not sacrifice for Abraham, Isaac, Jacob, and all the prophets? Is there really more than one way to get to Heaven?
Of course His sacrifice was "retroactive." Remember St. John Chrysostom's Paschal (Easter) homily Kolo posted so many times? Remember the icon of Christ breaking down the gates of hell and pulling out of the hands of death the OT righteous? (that's not biblical though!).
My point was that until His sacrifice on the cross, no one was saved. But He made it possible for the whole world to be saved, past, present and future.
My only problem is with the appearance of Moses at Mt. Tabor.
So, are you saying that Jesus did not sacrifice for Abraham, Isaac, Jacob, and all the prophets? Is there really more than one way to get to Heaven?
No & no. :)