This was brought up to me by a protestant friend of mine. These are not my thoughts. I am not sure how to answer or what to think of this. It sounds very relativistic to me.
what ever occurs or doesn’t occur during the Lord’s Supper happens to ALL Christian believers, regardless of their theology. The Lord’s Supper was instituted by God: by Christ while He was here on earth. We can try and understand what happens and what it means, but ultimately, it is what God made it, and not what we think it to be. The Sacrament came before the theology: it is what God intended it to be, not what we theorize it to be.
As a catholic, I believe that the eucharist is the body and blood of Christ. And that our priests, through apostolic succession, have the power and authority to make it so. I don’t believe other faiths have that, nor do I believe it would be the same as receiving in another faith. So I don’t believe it is the same for all christian believers. I think God intended the sacrament to be conducted by His one true church, in the proper form. I don’t believe it is all the same.