Christmas is not Christmas without the message of the death and resurrection of Christ. This is why He was born. His name has been Jesus alone. He was to save His people from their sins primarily.
The Prophet Isaiah said that His name would be called Immanuel, which means God with us (Isaiah 7:14, Matthew 1:23). 
at the end of Matthew’s Gospel the risen Jesus promises to be with us “always, until the end of the age” and so from beginning to end, Jesus is (and continues to be) Emmanuel.
This is why faithfully we celebrate his existence (birth).
“whoever believes in Him will never ever perish but live an everlasting life” John 3:16