Today is Dietrich Bonhoeffer’s birthday. Since my book on him was published three years ago, fascination with the young German pastor continues to grow. The interest is so great I’ve recently been asked to do a ten-city Bonhoeffer tour. I have to ask myself: Why are so many people intrigued by Bonhoeffer? The answer, I believe, is that the message of Bonhoeffer's life is hugely relevant today—especially when it comes to the growing threats against religious freedom. Thoughtful people see the handwriting on the wall: First there's the HHS mandate, which demands that religious organizations buy insurance that covers abortion-inducing...