Jesus never asked his disciples to remember His birth, but He did instruct them to remember His death and resurrection.  He gave the church two visible symbols (called “ordinances”) as reminders of His death.  These two ordinances are Baptism and the Lord’s Supper. 

Baptism and the Lord’s Supper are distinguished clearly from other ceremonies because both of them preach the Gospel.  Just as a pastor may preach about Christ’s death and resurrection so that men may hear it, so baptism and the Lord’s Supper preach about Christ’s death, burial, and resurrection.  In the supper, the pieces of bread speak of Christ’s body broken by scourging and thorns, swords and nails.  The juice speaks of Christ’s blood which was spilled during His execution.  This is a very important thing to say about the ordinances:  They preach the Gospel!  In them the gospel is being enacted before the church like a play on stage.