If a person does not believe the host is the body and blood of Christ, does that change what happens when he receives it?
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.