As a hat, four people holding a cross use an umbrella. The umbrella is big enough to be a hat for all four people, so it makes sense. All four of them are religious missionaries, so that’s why they’re holding the cross.
You know the Spanish phrase “Mi casa (かさ) es su casa”? Well this is kind of like that, but only with a hat. And that hat is an umbrella. Mi casa es yours too, because it’s an umbrella and also a hat. This makes sense, trust me.