There seems to be a general misconception about what eternity means. Most people seem to think that it is from now until the end of time. In other words, they believe that eternity exists in the future. And, in a way it does. But that is only half of eternity. Of course, this is still a very long time but only half as long as it really is. This is really forever.
"But wait!" you say. Forever is also used to express the past. "I've been waiting for this bus forever." "It's taking forever to type this article." The past is forever, too.
Forever is the future and the past.
Eternity is the present. Think about it. It has no beginning and no end; no past and no future. It just is. Therefore, the faithful believer who is saved to eternal life has no beginning and no end. All the sins one ever committed are erased, as are all the sins one ever will commit. There are no "special" days because all the days belong to the LORD who is eternal. All days are as one to Him. This is not to say that it is wrong to set apart holidays to remember specific holy events. I thoroughly enjoy Christmas and Easter and such. They are awesome times of worship and celebration. Furthermore, since everyday is equal to our Eternal God, the specific day these fall upon every year doesn't matter either. Nor does the name we use for these holidays matter.
Eternity is now. To have eternal life is to have it now and forever (present +past and future). The theological implications of this are endless (they'd have to be, though, wouldn't they?). I could go on and on. So, I'm sure that I will return to this topic in the "future".