Harun Yahya
10-5-2018 | IslamWeb
Question:
What is your advise regarding the person Harun Yahya (real name Adnan Oktar)? Is he dangerous and does he have some sort of agenda against Islam? He dances with almost naked woman on the tunes of music, wears gold, hasn't written any book himself, doesnt have a proper beard and most importantly his over all lifestyle depicts him to be least trustworthy. I know generally you dont speak about person on this website but I must say this case must be treated as an exception. As there is more benefit about having a ruling on him than simply saying "we will not comment on him". His works may delude many and kindly advise us.
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad 
is His slave and Messenger.
What you mentioned in the question is true. Indeed our Fatwa Center is not concerned with judging people, but after looking into the case of this man, it became clear that it is a very serious case and it is an obligation upon us to warn against him. He has a deceitful way; on one hand he writes about atheism, responds to atheists, and criticizes Darwin's theory with Islamic and logical evidence, a matter that may lure people with his writings. At the same time, he calls to very dangerous ideas; he calls to the so-called common faith between the people of heavenly religions (interfaith), and he claims that the Jews and Christians are not disbelievers. By saying so, he contradicts the clear texts of the Quran and the Sunnah that confirm that they are disbelievers, and that call them to believe (in Islam).
There are many verses in this context. The evidence from the Ahadeeth is that which was narrated Abu Hurayrah 
that the Prophet said: "I swear by Him in Whose Hand the soul of Muhammad is, there is no Jew or Christian of this nation (of people from the time of the Prophet until the Day of Judgment) who hears about me and then dies without believing in what I was sent with, except that he will be amongst the people of Hellfire." [Muslim]
For more details on this issue, please refer to the following Fataawa: 2924 and 12718.
If in addition to these wrong ideas, he does the evil acts that you mentioned, then his matter is darkness upon darkness.
Therefore, it is an obligation to beware of him, and it is an obligation to warn against him. His books must not be read, and his talks must not be listened to except for he who wants to refute his saying and warn against him, provided that the one who dies so has a deep Islamic knowledge to protect himself from the misguidance and misconceptions of this man.
Allah knows best.