In matters of Dunya we should indeed not pay attention to idiots as it is a waste of time.
However, when it comes to matters of Deen and if the "idiot" is propagating falsehood and there is danger to the Eemaan of others and the person is certain about the falsehood then the person has no choice but to intervene and get abused, slandered and humiliated because it is the DEEN of Allah Ta'ala and others at risk.
A person who has certainty in knowledge and does not intervene will be questioned by Allah Ta'ala on the day of judgement. However, the intervention needs to be proportional to the matter and its status in Shariah e.g. if something is Mustahab then don't intervene with the ferociousness of defending or enforcing a Fardh or Waajib act.
This matter is discussed by Shah Wali Ullah (RA) in Hujjatullahil-Baaligha which is a MUST READ for every Muslim in our times to combat ideological heresy etc.
P.S: Hit "dislike" and move on...
This cannot be undone and I am sure it will be greatly appreciated.