Why use a household to illustrate this division? Because the closest bonds are tested most fiercely.
Jesus often used everyday scenarios to explain spiritual truths. Here, he paints a picture of a family – the most intimate unit. He suggests a typical family might consist of five people (father, mother, son, daughter, and daughter-in-law, or son's wife). When the Gospel message enters such a home, it doesn't automatically unite everyone. Instead, it can expose the deepest fault lines. Some will embrace Christ's teachings, while others will reject them. This creates a stark division: three are on one side, two on the other, and vice-versa. The core of the Gospel's impact is its power to reveal true allegiance.