Notre Dame's invitation to President Barack Obama to give the commencement address and receive an honorary degree on May 17th met with criticism from many Roman Catholics across the nation.  After all, as these critics argued, Obama's pro-choice stance on abortion and his policy on stem-cell research are condemned by the Roman Catholic Church.  The formal protests began in earnest in early May, and on Friday, May 15th, a Catholic priest, political activist Alan Keyes, and nineteen others were arrested for trespassing while marching in protest on the campus of Notre Dame.  Several individuals and groups at Notre Dame have also spoken up against the University's decision, including Father John Corapi and conservative student groups on campus.     While images of angry protesters may grab our attention, perhaps the most interesting and relevant aspect of this story lies in the different reactions among Roman Catholics.  Indeed, a Amy Sullivan takes up just this question in an article posted on the Time website on May 16th.  Sullivan points to the outrage among conservative Catholics in America on the Obama issue, on the one hand, while citing the approval of or indifference to the issue among many American Catholics.   Sullivan also points out that the Vatican "has stayed completely silent on the matter," arguing that papal policy has often been to let local bishops do the heavy lifting when it comes to controversial issues that could damage the Pope's relationship with other heads of state.  She adds that for the "small but vocal group of conservative Catholics, the episode has become an opportunity to draw lines between those who are genuinely Catholic and those whom they accuse of being Catholic in name only - even the head of the country's premier Catholic university."    This question of what it means to be Roman Catholic has been around for centuries, and variously articulated around a number of "hot-button" issues.  For example, in the late sixteenth century, many Catholic lords in the Holy Roman Empire felt that the only way to maintain peace in their lands was to allow their subjects to receive communion sub utraque specie, that is, to receive both the bread and the wine during the Eucharist.  They feared that strict adherence to the Church's teaching that the laity were to receive communion sub una specie (the bread alone) would impel many to join the followers of Luther and Calvin, who all communicated under both kinds.  Thus, under pressure from Emperor Ferdinand I, Pope Pius IV ceded the cup to the laity in Bavaria, Austria, Hungary, and the Bohemian Kingdom in 1564.     At the time, many Catholics believed that communion sub una specie was the most important marker of Roman Catholic worship against that of the Protestants.  To conservatives such as the Jesuits, the concession of the chalice to the laity signaled the abandonment of their Roman Catholic identity.  One polemicist went so far as to publish a work outlining ten reasons why lords in the Empire should want to be called "Roman Catholic" instead of simply "Catholic."  Like many conservatives today, the author alleged that there were a lot of people who claimed to be Catholic but did not follow the teachings of the Church; "Roman Catholics," however, did.  Ultimately, communion under both kinds was rescinded in these Imperial territories, but in the case of Bohemia and Moravia, the return to communion under one kind did not happen until 1621.   The issues at stake today, while different, are also regarded as important markers of Roman Catholic identity.  Just as one's position on communion under one kind in the sixteenth century (or one's stance on modern liberalism in the nineteenth century) could be used to identify someone as a "good" or "bad" Roman Catholic, it is clear that some Catholics today have identified abortion and stem-cell research as issues about which one must take a stand - but other Catholics clearly have not.  Divergent ideas about what it means to be Catholic are as old as Catholicism itself, but the Notre Dame commencement controversy and the issues it brings to the fore remind us to keep our eyes on how the battle-lines are being drawn between the more conservative and more liberal Roman Catholics - and who draws them.     Reference: http://www.time.com/time/nation/article/0,8599,1898756,00.html     Adam W