 in order to save on their utility bills. Scott Horsley, NPR News, Washington. Tens of thousands of Catholics have gathered in Indianapolis for an event called the National Eucharistic Congress. It celebrates the highlight of the Catholic Mass, the Eucharist, a wafer given to Catholics during Mass. Roman Catholic Church doctrine teaches it's the reality of Christ given to them. Over the past two months, Catholic pilgrims across the country have traveled four routes to reach the Indianapolis event.