Is it Gheeba (backbiting) to talk badly of someone’s professional ability or about his/her public roles? For example, is it Gheeba to say that a doctor isn’t very good at what they do, or a scholar isn’t very good at fiqh, or a speaker isn’t a very good speaker? Is it Gheeba if the scenario is different and one would say, I don’t like this person because he does not pray or fast, or he does not support an ideology I hold dear?
Backbiting is impermissible. It is when one ‘says something about his brother which Allah has concealed about him’. It occurs when a believer is spoken about in his absence, by mentioning a deficiency in that person which is concealed, in front of a third party. This is considered backbiting, even if the person being spoken about does not object to this, and even if the purpose is not to belittle the person. However, when it comes to deficiencies which are apparent in that person, relating them to a third party is not considered backbiting.
As for criticising a person’s ability to perform their professional role, this should be limited to situations where its benefits are more than its harms and one should be sure that they are mentioning facts and not exaggerating in order to hurt that absent person’s reputation without good evidence.
As for criticising a person for sinning, this is not backbiting as long as a person is doing this openly. If they are sinning secretly (e.g. they pray in public, but do not in private) then it is backbiting to relate this private issue to a third party and this is haram.
When it comes to ideology, as long as a person is a believer, we should not criticise them. Yes, we may argue academically against their ideology, but we should not make it a personal issue. Instead, we should try to build unity amongst believers by finding common ground and reasons for liking each other rather than disliking each other.
In the authentic narration of Abdul Rahman ibn Siyaba it is related: “I heard Abu Abdullah (Imam Sadiq as) saying: ‘backbiting is to say about your brother that which Allah (swt) has concealed about him. As for mentioning apparent things about that person, such as being a stern person or a hasty person, this is not backbiting'”.