Why Do We Celebrate Communion?

Jesus celebrated "the last supper" with his disciples as a pre-enactment of his sacrifice which was the greatest Passover and Exodus for the people of God.  
The church now celebrates the communion meal as a way to remember and proclaim the gospel: that the cross is the great equalizer that cuts us to our knees in humility and then raises us to status with Jesus as heirs of the Kingdom.