Question: Is it permissible to mention peoples names and characters when one wants to criticize them and their thinking?
Answer:
If someone writes something that contradicts the pure Shari' ah, and distributes that material, or if he promulgates that view in the media, it becomes compulsory to refute him and expose the falsehood of what he says. There is nothing wrong in mentioning that person's name or in warning people about him if he calls to innovation, shirk, or if he calls people to what Allah has prohibited or to disobedience. Until this day, there are knowledgeable and believing people from the callers to the truth and bearers of the Shari ah fulfilling this obligation, sincerely for Allah Almighty and for the benefit of His servants, rebuking the wrong, inviting to the truth, warning others against those who propagate falsehood and destructive rhetoric.
Shaykh `Abdul-`Azeez Bin Baz
Fatawa Islamiyah Darussalam Vol 8 page no.53
Source: http://www.fatwaislam.com/fis/index.cfm?scn=fd&ID=1076
The Methodology of Ahl-us-Sunnah wal-Jamaa'ah in Warning Against Innovators and Their Books
Author: Shaikh Rabee' bin Haadee al-Madkhalee
Source: book Manhaj Ahl-us-Sunnah wal-Jamaa'ah Fee Naqd-ir-Rijaal wal-Kutub wat-Tawaa'if
Article ID : BDH050002
http://www.spubs.com/sps/sp.cfm?subsecID=BDH05&articleID=BDH050002&articlePages=1