Transubstantiation. Belive.

Transubstantiation – the idea that during Mass, the bread and wine used for Communion become the body and blood of Jesus Christ – is central to the Catholic faith. Indeed, the Catholic Church teaches that “the Eucharist is ‘the source and summit of the Christian life.’”
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But a new Pew Research Centre survey finds that most self-described Catholics don’t believe this core teaching. In fact, nearly seven-in-ten Catholics (69%) say they personally believe that during Catholic Mass, the bread and wine used in Communion “are symbols of the body and blood of Jesus Christ.” Just one-third of U.S. Catholics (31%) say they believe that “during Catholic Mass, the bread and wine actually become the body and blood of Jesus.” 

Read more here: "Just one-third of U.S. Catholics agree with their church that Eucharist is body, blood of Christ." ​/www.pewresearch.org