Luther writes that in the Sacrament of the Altar, there is a profound union. “For there is no more intimate, deep, and indivisible union than the union of the food with him who is fed. For the food enters into and is assimilated by his very nature, and becomes one substance with the person who is fed” (AE 35: 59). The resultant effect is that our sins assail Christ, who is invincible, while His righteousness protects us who are mortal. This argument—the assimilation of the food into the human nature—already lays the foundation for Luther’s later contention for the bodily benefit that accrues to the communicant.
But what is surprising (and goes against those with the mechanistic view) is that, in Luther’s thought, this “assimilation” and transformation actually affects the life of the Christian. Through the love given to us by Christ, we are “to be changed and make the infirmities of all other Christians our own…” (AE 35: 58). All good within our power we are to give to them. “That is real fellowship, and that is the true significance of this sacrament. In this way we are changed into one another and are made into a community by love.”
So, what are the the tangible aspects of the “fellowship” of Christians? Luther elaborates:
But in times past this sacrament was so properly used, and the people were taught to understand this fellowship so well, that they even gathered food and material goods in the church, and there—as St. Paul writes in 1 Corinthians 11—distributed among those who were in need.… Those were the days too when so many became martyrs and saints. There were fewer masses, but much strength and blessing resulted from the masses; Christians cared for one another, supported one another, sympathized with one another, bore one another’s burdens and affliction (AE 35: 57).