In the church calendar, the Thursday before Easter is called Maundy Thursday. It's set aside to remember the last supper Jesus shared with his disciples.
The word "maundy" comes from the Latin word for command. At this supper. Jesus commanded His disciples to love and serve one another. And then he demonstrated what he meant by washing their feet. And let's not forget: This was the supper remembering Passover, when the Jews remember God rescuing His people from Egypt, as described in Exodus. At this supper, Jesus revealed himself as the fulfillment of that event.
It's His broken body and shed blood we are to remember. So is Christianity service or salvation? This divided the church in the 20th century and still does today. The answer is, it's both. On the same night, Jesus commands us to remember that we need rescue by His broken body and spilled blood, and to show we have been rescued by loving and serving each other.