You wrote:

A closer analogy to the silence of the imams is the silence of the Christian clergy, including the Pope, in the face of Nazi persecution of the Jews. One need not be the source of evil to be afraid to confront it. Does that historical moment define Christianity?

The Vatican is located in Rome, which was also the home to the Fascists under Mussolini. Italy was also occupied by the Nazis. The Vatican had to step carefully under those circumstances. There is some evidence showing that particular Pope may have been antisemitic. If so, his was an all too common view at the time. It's possible that his views might've shaped the Vatican's apparent lack of response. We could also look to other countries like Switzerland and Sweden and ask why they didn't do more to help fleeing Jews. It was all a rather sorted business.

However, I see no direct parallel with the Vatican's position in WWII with Imams in America and Europe today. They can speak out against extremism without fear of government prosecution. The situation is different in many other countries but not in Europe and America. As it is, their silence is deafening.

"In the End, we will remember not the words of our enemies, but the silence of our friends."
-- Martin Luther King Jr.