How do Christians celebrate birthdays?

Answer 1

Many celebrate in much the same way as the rest of whatever culture they are part of. Some Christians do not observe birthdays because of a belief that it is glorifying the self, neither was it practiced in the early church nor mandated by God. Others use it as an opportunity to celebrate the gift of life given to that particular person.

Answer 2

By being grateful to God that he loved us so much that he gave his only begotten son so that we would be saved. By also being grateful to Jesus Christ that he would sacrifice himself and lay down his own life for us. Most Christians go to church as part of the celebration. Some people have a feast in celebration, some people give each other presents because of their love for one another. It doesn't have to be an expensive present, it can be home-made like a card or cookies. People don't have to exchange presents, if they can't afford it, they can just tell people how much they love and appreciate them in their lives.