“For 2000 years many millions of Catholics (and even Luther) believe in the TRANSUBSTANATION.”
Just a mild correction - Luther/Lutherans do not believe in transubstantiation. We do accept the real presence of Christ physically in the Eucharist. This is supported both Biblically and by the writings of the Church Fathers:
“1] Of the Sacrament of the Altar we hold that bread and wine in the Supper are the true body and blood of Christ, and are given and received not only by the godly, but also by wicked Christians.” Smallcald Articles, Part 3, Article 4.
However, the concept of transubstantiation is not accepted by Luther or Lutherans (or Eastern Orthodox, as I understand it, one may correct me if I’m wrong there), which we feel to be no more than sophist mumbo-jumbo.
“5] As regards transubstantiation, we care nothing about the sophistical subtlety by which they teach that bread and wine leave or lose their own natural substance, and that there remain only the appearance and color of bread, and not true bread. For it is in perfect agreement with Holy Scriptures that there is, and remains, bread, as Paul himself calls it, 1 Cor. 10:16: The bread which we break. And 1 Cor. 11:28: Let him so eat of that bread.” - Smallcald Articles, Part 3, Article 4.
The doctrine of the Real Presence is necessarily contained in the doctrine of transubstantiation, but the doctrine of transubstantiation is not necessarily contained in the Real Presence. Christ could become really present without transubstantiation taking place, but we know that this is not what happened because of Christ’s own words at the Last Supper. He did not say, “This bread is my body,” but simply, “This is my body.” Those words indicated a complete change of the entire substance of bread into the entire substance of Christ. The word “this” indicated the whole of what Christ held in his hand. His words were so phrased as to indicate that the subject of the sentence, “this,” and the predicate, “my body,” are identical. As soon as the sentence was complete, the substance of the bread was no longer present. Christ’s body was present under the outward appearances of bread. The words of institution at the Last Supper were at the same time the words of transubstantiation. If Christ had wished the bread to be a kind of sacramental receptacle of his body, he would surely have used other words, for example, “This bread is my body” or “This contains my body.”