At what point does the body and blood of Christ appear/join the bread and wine during our service? Is it when the pastor says the words of institution?
Part VI of This We Believe, a statement of belief of WELS, addresses—with Scripture passages—your questions.
“We believe that all who join in the Sacrament of the Lord’s Supper receive the true body and blood of Christ in, with, and under the bread and wine (1 Corinthians 10:16). This is true because, when the Lord instituted this sacrament, he said, ‘This is my body. This is my blood of the covenant, which is poured out for many for the forgiveness of sins’ (Matthew 26:26,28). We believe that Christ’s words of institution cause the real presence—not any human action. As believers receive his body and blood, they also receive the forgiveness of sins (Matthew 26:28) and the comfort and assurance that they are truly his own. Unbelievers also receive Christ’s body and blood, but to their judgment (1 Corinthians 11:29).”
“We reject any attempt to set the precise moment within the celebration of the Lord’s Supper when the body and blood of Christ become present. We therefore reject the view that one must believe that Christ’s body and blood are present as soon as the words of consecration have been spoken and the view that one must believe that Christ’s body and blood become present only at the moment of eating and drinking.”