In the Lord’s supper as a memorial of Christ’s death. The bread symbolizes His broken body and the cup symbolizes His shed blood to commemorate atonement for sin.
When the hour came, Jesus and his apostles reclined at the table. And he said to them, "I have eagerly desired to eat this Passover with you before I suffer. For I tell you, I will not eat it again until it finds fulfillment in the kingdom of God." After taking the cup, he gave thanks and said, "Take this and divide it among you. For I tell you I will not drink again of the fruit of the vine until the kingdom of God comes." And he took bread, gave thanks and broke it, and gave it to them, saying, "This is my body given for you; do this in remembrance of me." In the same way, after the supper he took the cup, saying, "This cup is the new covenant in my blood, which is poured out for you.
I Corinthians 11:17-34
In the following directives I have no praise for you, for your meetings do more harm than good. In the first place, I hear that when you come together as a church, there are divisions among you, and to some extent I believe it. No doubt there have to be differences among you to show which of you have God's approval. When you come together, it is not the Lord's Supper you eat, for as you eat, each of you goes ahead without waiting for anybody else. One remains hungry, another gets drunk. Don't you have homes to eat and drink in? Or do you despise the church of God and humiliate those who have nothing? What shall I say to you? Shall I praise you for this? Certainly not! For I received from the Lord what I also passed on to you: The Lord Jesus, on the night he was betrayed, took bread, and when he had given thanks, he broke it and said, "This is my body, which is for you; do this in remembrance of me." In the same way, after supper he took the cup, saying, "This cup is the new covenant in my blood; do this, whenever you drink it, in remembrance of me." For whenever you eat this bread and drink this cup, you proclaim the Lord's death until he comes. Therefore, whoever eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of sinning against the body and blood of the Lord. A man ought to examine himself before he eats of the bread and drinks of the cup. For anyone who eats and drinks without recognizing the body of the Lord eats and drinks judgment on himself. That is why many among you are weak and sick, and a number of you have fallen asleep. But if we judged ourselves, we would not come under judgment. When we are judged by the Lord, we are being disciplined so that we will not be condemned with the world. So then, my brothers, when you come together to eat, wait for each other. If anyone is hungry, he should eat at home, so that when you meet together it may not result in judgment. And when I come I will give further directions.