What is the ruling on attributing a person to a specific group in order to belittle him?

Question:
If someone belittles another, for example, by saying, "This is a Salafi," or "This is a Tablighi," or "This is a Muslim Brotherhood member," and so on, with the intention of belittling the person, is this considered backbiting?

Answer:
No, mentioning him in this way is not backbiting. Mentioning him with what he has made public is not backbiting. He is the one who made himself public; he is the one who exposed it.
Q: A person said, for example, "This is a Salafi," meaning to mock him, for instance, meaning that he praises himself, or something like that. Or, for example, he said, "This person is not important to you; he is a Muslim Brotherhood member," or "This person, for example, is a Tablighi"?
The Shaykh: If there is a religious innovation in it, and one advises against it, describing him as such and such, meaning he is from the people of innovation, there is nothing wrong with it. One conveys this about him so that people may be warned.