Christians celebrate the birth of Jesus, and they celebrate by bonding with people nearby. They would smile. Smiling is pleasant and is a gift in some ways. Some people give money and kindness and...
It would still be Christmas because it is still a celebration of Christ's birth. And it doesn't matter if we do not give material things, because presents are gifts in a way that they come in so many...
presents on Christmas is kind of a reward if you have been good for the year... but if you are not good you wont get presents (or not as many). hope this helps :D