I apologize if i did this wrong because this is my first post, but I’m sorry to say Constantine, when Jesus said “ALL of you” at the Last Supper, He did not mean everyone may receive, non-Catholics and Catholics alike. Only those baptized into the Church may receive the Most Blessed Sacrament, and preferably those who have received penance and have a general knowledge of the Eucharist.
Now the mentally handicapped may also receive, but if their disability is to the extent that they cannot sin, there would be no reason for them to receive because they are sinless and thus they really do not need it. i know this because my cousin has severe brain damage and has received the Most Blessed Sacrament. even she had to go through a "training"though to get a general knowledge of the Eucharist.
Also, The only reason the Orthodox may receive is because they maintain apostolic succession. No other Christian church my receive the Eucharist, because they have no apostolic succession so they don’t have authentic priests. Now would it be nice for everyone to receive OUr Lord? of course and it is His will for everyone to receive. But either through their spiritual blindness or simply because of ignorance through no fault of theri own, many cannot see what the Blessed Sacrament truly is and do not know that our Church is the one true Church. But in the end, not everyone may receive. Only Catholics and Orthodox. I know it may sound exclusive and surely our loving Lord would never do such a thing, but it is the Truth.