Re: Is their a Quranic ruling for insulting and mocking Islam and Prophet (p.b.u.h.)
So much wrong at so many levels in your post but it would be good if you can post a reference to Marwan the caliph’s dad’s repentance story because I have never seen one. Maulana Maududi in his book Khilafat aur Malukiyat (pg. 110-111) criticizes in details and with references Marwan’s proximity to caliph Uthman particularly when Marwan’s father was alive and was capable of influencing the government affairs. As for Marwan himself, here is the kind of CV that he carried:
-Killing Talha bin Obaidullah and other companions.
-Beating Abdullah ibne Masud, Ammar bin Yasir for voicing against corruption.
-Expelling Abu Dharr al Ghaffari from Medina into desert which results in his death along with his wife.
-Ordering arrows to be shot at the funeral of Imam Hasan.
-Forging letter in caliph’s name and ordering oppression such as killing of Egyptian envoy who had come to Medina to complain of oppression.
-Threatening to kill Imam Hussein in Medina.
-Killing of Muawiya ibne Yazeed whose mother he married to earn the caliphate.
And these are only some of his credentials. He was nicknamed 'Khabtul Batil meaning “the head of evil”.