By Paul Kengor

Spencer Platt/Getty Images
A mural to fallen firefighters is seen covered by scaffolding in Manhattan on Sept. 9 in New York City. New York City and much of the nation are preparing for the 20th anniversary of the terrorist attacks in both New York City and Washington D.C.

COMMENTARY: Catechism Section 409 provides clarity on the 20th anniversary of unspeakable evil.

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