I know this is a joke. It's a generalization, see, saying that generalizations are all false... but something must be said.

We cannot live without generalizations. If we don't generalize that because we have gotten hungry in what looks like a pattern of passage of time, then act on that generalization, we'll be unhappy by bedtime.

Mark Twain tells of a cat that like to sit on the wood-burning stove in the kitchen. It had never happened to jump up on it when it was hot. One day, it did. That cat never jumped up on a hot stove again.

But the cat made the wrong generalization and also never jumped up on a cold stove. The lesson learned was not to jump up on the stove instead of not to jump on the stove when it's hot. So while generalization can help, the wrong lessons also can be gleaned from them.

I can think of several people in that church who don't fit that generalization. That does not make the generalization untrue. Instead we are called on to recognize that a generalization is not a description of all things, but a description of a tendency or the plurality or situations.