At Yad Vashem, the Holocaust museum in Israel, my husband and I went to the Righteous Among the Nations garden that honors the men and women who risked their lives to save Jewish people during the Holocaust. While looking at the memorial, we met a group from the Netherlands. One woman was there to see her grandparents’ names listed on the large plaques. Intrigued, we asked about her family’s story.

Members of a resistance network, the woman’s grandparents Rev. Pieter and Adriana Müller took in a two-year-old Jewish boy and passed him off as the youngest of their eight children from…