Jesus invites us to take part in his Body. He offers to us everything that he respresents and has accomplished, the body of his work so to speak. Not only that but he has also made it possible for us to take part in it by shedding his blood to cover the sins of the world. These two things are what communion, or the Lord's supper are all about. Participating in communion with other believers is not just an opportunity to remember what Jesus has done but to proclaim the truth of the gospel to one another. Jesus had the very first communion with traitors and cowards, and for you and me he invites us into that same fellowship.