Want to start a fight? Just ask this question: How many Protestant denominations are there in the world?

Estimates start as high as 40,000 and most sources put the number above 20,000, citing the United Nations, the World Christian Encyclopedia or some other authority. The key is that various Protestant groups have their own concepts of biblical authority and the role played by the conscience of each believer. Fights often cause splits and new flocks.

Meanwhile, the Church of Rome has the Throne of St. Peter and the Catechism. This is why eyebrows were raised when progressive theologian Daniel Maguire of Marquette, amid tense debates about marriage, divorce and gay rights, wrote to The New York Times to argue that Catholicism is "going the way of its parent, Judaism" and dividing into three streams.

"In Judaism there are Reform as well as Conservative and Orthodox communities. This arrangement is not yet formalized in Catholicism, but the outlines of a similar broadening are in place," said Maguire. While the Vatican may tweak some procedures, such as streamlining the annulment process, "reform Catholics don't need it. Theirconsciences are their Vatican."

The tricky word "conscience" crept into news about the 2015 Synod of Bishops in Rome -- focusing on marriage and family life -- when the leader of the giant Archdiocese of Chicago told reporters that he thought many Catholics who under current teachings cannot take Holy Communion should be able to do so, if guided by their consciences.