Why can't you guys buy into a 6 day creation if you so readily accept that something that is by all "appearances" bread is really human flesh?
Because the Church sees the Gospels as eyewitness accounts of Jesus' ministry, while the Pentateuch, the prophets, and apocalyptic literature employed both literal recounts and literary devices unique to the time those texts were written. The Catholic Church, going back even to Saint Augustine, has maintained that the story of creation is not to be taken as a literal unfolding of a week of 24-hour days. It's impossible even from a literal stand point since God did not create time until the fourth "day". How were the first three days "marked", exactly?
Augustine believed that the "six days" were actually one "day" - you know - "this is THE DAY the Lord has made". (Sirach: "God created ALL THINGS SIMULTANEOUSLY"); And that this single "day" is re-presented six times to the reader (or listener) of Sacred Scripture as a means of condescending to our finite brainpower and general lack of understanding of how God thinks and behaves. It goes much deeper than that, however. You have to understand the importance of numerology in Old Testament society to know that the number "seven" in Hebrew ('sheva') means "to swear an oath [upon something]". In the story of creation, God builds Himself a house to dwell in (earth and all its inhabitants). On the seventh day, He "sevens" Himself - He swears an oath upon Himself and accepts Adam (man) as a member of His family, as part of this household He's set up. Of course, Adam and Eve promptly throw that gift away. Man becomes alienated from God's family due to Original Sin, which is expiated through Baptism, when Catholics teach that a person (infant, child, adult, whatever) is accepted into God's covenant established in Creation. But the early believers of Yaweh knew exactly what was meant by the use of "seven" days.
The seventh day, the time of "rest", is not just about giving the Sabbath as a day of rest - it also refers to the "day" when we enter God's rest in eternity.
And that's just for starters.
A prominent Catholic theologian (and former Protestant preacher) once said, "the Protestant churches love reading the menu (the Bible). They'll read it over and over and over and over... But they never sit down to the meal (the Eucharist)."
Why is it that Protestants believe that Christ could change water into wine at Cana, but couldn't change bread and wine into His body and blood? It doesn't compute.
In the miracle of the wine, the wine actually became wine in both appearance and substance. That is how we know it was a miracle. Jesus did not serve up a batch of water and tell everyone it was wine, he took the water and made it into wine and the people saw wine and the tasted wine. In the eucharist you have to take the word of the Priest or the Church that the wine is really blood. It is by all appearances wine. So no "miracle" has occurred. But it isn't wine and God is not lying to your senses. You taste wine because it is wine in both substance and appearance.
If a miracle like Cana occurred then you would taste blood. You don't because it isn't.