Do you really want to believe in Santa and the magic of Christmas again? Let me see if I can help your here. Maybe using physics we can make out dreams come back to life.
Lets start with just talking about how many presents he would need to deliver. There are roughly 2 billion kids in the world, taking out all the non-Christian kids, that leaves around 378 million children give or take. Now taking the average of 3.5 kids per household, this leaves us with 91.8 million household he must get to in 31 hours (thanks to time zones.)
I think the first thing we need to look at is the weight of the sled. Lets just say every kid gets just 1, 1 kilogram present. That's 378 million kilograms on his sleigh. To get going he would need to move at around 2,800 kilometer per second, roughly 1/100th the speed of light. Also every time he stopped he would need the energy equal to the amount found in a small star.
There are other factor to think about too. There is the fact that he is moving so fast that he would burn up and the amount of energy he is exerting would vaporize him and his reindeer. On top of that he only has about 1/100th of second to stop at each house. Some more things are explained here:
Now, with all these numbers it does appear that if Santa did attempt to deliver present he died. But I want to believe. Whose say that with all the undiscovered species on this planet whose to say there isn't an unknown species of flying reindeer. Or maybe Santa is a physics genius and has technology far beyond us and has gotten pasted of all these problems. All you got to do is believe.