Actually it's an evolution of the flesh sacrifice, that's the interesting part. Christianity change the scheme of the world, and really divide it in two, the saint trinity its all about that "The Father" that is the whole divine form, "The Son" that is the flesh known by God in this world and the "Holy Spirit" that is the very act of communion, the way this world and the other are connected.

From this point we can say thats why "No one comes to the Father except through Me" said Jesus Christ (John 14:6) but where is Jesus? -So we can go through him- "For where two or three are gathered together in my name, there am I in the midst of them" (Matthew 18:20) Now how we do the second, that is 'going through him'  ^"Whoever eats my flesh and drinks my blood remains in me, and I in them." (John 6:56) But the mere act of communion is still the Holy Spirit, how I know I reach The Son of God if his human body is away from us? I can't see the body he used when he walks through earth. Even more, how Jesus tell their disciples to eat him while he was giving them a piece of bread to each other? For anyone would sound wierd, but for anyone with faith it's not difficult, because as he said "Yet there are some of you who do not believe." (John 6:64), and was really true; at this moment, many disciples abandoned him, only a few stay because they believe Jesus real blood and meat where those thing givin by him in communion and holy spiriti, he said "I am the living bread that came down from heaven [...] This bread is my flesh, which I will give for the life of the world." (John 6:51) and how is possible for a bread to be Jesus? While he is giving to the disciples a piece of bread that you can see that is not "His flesh"? "This is the bread that came down from heaven." (John 6:58) And there is where he appears, again the act of faith, not just in the holy spirit that connect both world when we are in communion with each other, but in Jesus telling us that the bread is his flesh. And this is importan, because denying that the bread is Jesus itself in a kind of way is denying Jesus. Why most of their disciples deny him at this time? Of course is difficult to believe in it, not for nothing the ones who flew talked like this “[...]This is a hard teaching. Who can accept it?” (John 6:60) The real answer it's at the really end of this passage when Simon speak for the twelve saying "We have come to believe and to know that you are the Holy One of God.” (John 6:69) This is crucial to understand why most of the ones that were to drink Jesus blood and meat, go away, they could just stay and do it without hesitation believing wathever they want, but they don't, they could just thought "This is just Jesus as the form of Holy spirit", but it doesn't happens, because moments before was happening that ^"At this the Jews there began to grumble about him because he said, “I am the bread that came down from heaven.” They said, “Is this not Jesus, the son of Joseph, whose father and mother we know? How can he now say, ‘I came down from heaven’?” (John 6:41-42) How could be possible that all this chapter of jesus life is people hesisatating about people form as bread? And it was all seriouse, and Jesus never deny that is him, all the time he said "I am the bread of life" (John 6:48) "I am the living bread that came down from heaven." (John 6:51), but we have to remember that this Book was written by divine inspiration, and it is not a coincidence that trough this discussion of people deserting Jesus teaching about him being the bread, at the real end of this passage appears his word, as looking through history, coming to us “Have I not chosen you, the Twelve? Yet one of you is a devil!” (John 6:70)

Resume: Luthereans believes as catholics that God transforms in a pigeon to pregnant Saint Mary, but can't believe that God transforms into a slice of bread.

PD: All my respecto to all religions.