Europe has been shocked and outraged by Donald Trump's call to exclude Muslims from migration to the United States. A petition to have him banned from the United Kingdom gained far more than the 100,000 signatures necessary to force Britain's parliament to consider a debate on the issue. Yet what Trump had to say should feel outrageously familiar.

Populist bigotry about Muslims has already mainstreamed in Europe. Europeans haven't been outraged enough about that.

Take Marine Le Pen, whose National Front just won 28 percent of the vote — more than either of the main parties — in the first round of elections to run France's regional governments. Arguably she now has a better shot at becoming president in France than Trump has in the U.S. She has talked of Muslim immigration as an occupation, comparing it to the German occupation of France in World War II.