In the 19th century, Catholicism was regarded by many people in this country as thoroughly incompatible with Americanism. They saw it as a hostile foreign element that would subvert democracy. Today, a majority of the justices on the Supreme Court are Catholic, and they are taken to be as American as Mountain Dew. We've come a long way in religious tolerance, writes Steve Chapman. Or maybe not. The belief that Catholics are irredeemably alien and disloyal has given way to the fear that Muslims pose a mortal threat to our way of life.