Lutherans believe that Christ’s Body is truly present and His Blood truly present in the elements. We don’t hold to the belief that the elements cease to be bread and wine. We take Christ at his word when he says “this is my body.”
From 1 Corinthians: “Whoever, therefore, eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of profaning the body and blood of the Lord. Let a man examine himself, and so eat of the bread and drink of the cup. For any one who eats and drinks without discerning the body eats and drinks judgment upon himself.”
Also from 1 Corinthians: The cup of blessing which we bless, is it not a participation in the blood of Christ? The bread which we break, is it not a participation in the body of Christ? Because there is one bread, we who are many are one body, for we all partake of the one bread.
Paul doesn’t mention that the bread ceases to be bread. Therefore, we let it remain a mystery as to how Christ comes into the bread and wine, but we do believe His Body and Blood are present.