Christians take communion to remember Christ's sacrifice, to reflect upon their own spiritual health, to bond with Christ and because the Bible instructs them to do so. Communion is the consumption of wine and bread to commemorate the Last Supper. It is done periodically to commemorate special occasions and holidays.
Jesus held communion with his disciples during the Last Supper, which was the meal they shared shortly before Jesus was crucified, during which Jesus told the disciples that he would be gone soon and provided them with instructions about how to continue. During the meal, he told his disciples that when they drank from a glass of wine, they were drinking his blood, and when they ate a piece of bread, they were partaking of his flesh. Contemporary schools of thought about the bread and wine consumed during communion vary. For many, the bread and wine are simply symbolic. Others believe that Jesus' spirit enters them through their consumption. In the Catholic church, tradition dictates that the wine and bread actually transform into the blood and flesh of Christ. In some churches, the bread is replaced with crackers. In some conservative churches in which the consumption of alcohol is strictly forbidden, grape juice is used instead of wine.