When my oldest sister’s biopsy revealed cancer in late February 2017, I remarked to friends, “I need to spend as much time with Carolyn as possible—starting now.” Some told me my feelings were an overreaction to the news. But she died within ten months, and even though I had spent hours with her, when we love someone there’s never enough time for our hearts to love enough.

The apostle Peter called Jesus’s followers in the early church to “love each other deeply” (1 Peter 4:8). They were suffering under persecution and needed the love of their brothers and sisters in their…