If a person does not believe the consecrated host becomes the true body and blood of Christ, does that make a difference in what happens when he receives it? If he were given a shot of morphine, his belief that it is not morphine would not change the effects on his body. It would seem the same thing happens with the host. The body and blood of Christ enters his body and gives him grace, no matter what he believes.
Every one of the sacraments is a personal encounter with Jesus. Grace is a share in his life and in his love. He never forces his love on anyone. Certainly the reality of the presence of Jesus in the Eucharist does not depend on the state of soul of the communicant. He can receive the Eucharist as an act of sacrilege. But he cannot receive the grace of the sacrament without a proper attitude or disposition. It’s like going to the well without a bucket. The water is real. But without a bucket, he leaves without any water. Love is two ways. A person cannot enter into a love relationship without being willing to love.