Abu Bakr Mohammad Ibn Zakariya al-Razi, connu aussi comme Al-Razi, ou Ar-Razi, ou Ibn Zakaria (Zakariya) ou (en latin) comme Rhazes et Rasis, (865-925) fut un scientifique pluridisciplinaire iranien qui a énormément contribué dans les domaines de la médecine, l'alchimie et la philosophie. Alchimiste devenu médecin, il aurait isolé l'acide sulfurique et l'éthanol dont il initia l'utilisation médicale. S'agissant de la pratique médicale, il a vigoureusement défendu la démarche scientifique dans le diagnostic et la thérapeutique et a largement influencé la conception de l'organisation hospitalière en lien avec la formation des futurs médecins. Empiriste et rationaliste, il fut l'objet de nombreuses critiques pour son opposition à l'aristotélisme et sa libre-pensée vis-à-vis de la religion.
Ce que pensait Zakarya Razi des religions :
(Encore un qui doit se retourner dans sa tombe à chacun de ses expositions à l'Institut du Monde Arabe)
Il y a pas mal d'humour dans ses écrits à mon avis...
Razi wrote three books dealing with religion; they were: The Prophet's Fraudulent Tricks, The Stratagems of Those Who Claim to Be Prophets (Arabic حيل المتنبيين), and On the Refutation of Revealed Religions (Arabic مخارق الانبياء). He offered harsh criticism concerning religions, in particular those religions that claim to have been revealed by prophetic experiences. Razi asserted that "[God] should not set some individuals over others, and there should be between them neither rivalry nor disagreement which would bring them to perdition." He argued,
On what ground do you deem it necessary that God should single out certain individuals [by giving them prophecy], that he should set them up above other people, that he should appoint them to be the people's guides, and make people dependent upon them?
Concerning the link between violence and religion, Razi expressed that God must have known, considering the many disagreements between different religions, that "there would be a universal disaster and they would perish in the mutual hostilities and fightings. Indeed, many people have perished in this way, as we can see."
He was also critical of the lack of interest among religious adherents in the rational analysis of their beliefs, and the violent reaction which takes its place:
If the people of this religion are asked about the proof for the soundness of their religion, they flare up, get angry and spill the blood of whoever confronts them with this question. They forbid rational speculation, and strive to kill their adversaries. This is why truth became thoroughly silenced and concealed.
Al-Razi believed that common people had originally been duped into belief by religious authority figures and by the status quo. He believed that these authority figures were able to continually deceive the common people "as a result of [religious people] being long accustomed to their religious denomination, as days passed and it became a habit. Because they were deluded by the beards of the goats, who sit in ranks in their councils, straining their throats in recounting lies, senseless myths and "so-and-so told us in the name of so-and-so..."
He believed that the existence of a large variety of religions was, in itself, evidence that they were all man made, saying, "Jesus claimed that he is the son of God, while Moses claimed that He had no son, and Muhammad claimed that he [Jesus] was created like the rest of humanity." and "Mani and Zoroaster contradicted Moses, Jesus and Muhammad regarding the Eternal One, the coming into being of the world, and the reasons for the [existence] of good and evil." In relation to the Hebrew's God asking of sacrifices, he said that "This sounds like the words of the needy rather than of the Laudable Self-sufficient One."
On the Quran, al-Razi said:
You claim that the evidentiary miracle is present and available, namely, the Koran. You say: "Whoever denies it, let him produce a similar one." Indeed, we shall produce a thousand similar, from the works of rhetoricians, eloquent speakers and valiant poets, which are more appropriately phrased and state the issues more succinctly. They convey the meaning better and their rhymed prose is in better meter. ... By God what you say astonishes us! You are talking about a work which recounts ancient myths, and which at the same time is full of contradictions and does not contain any useful information or explanation. Then you say: "Produce something like it"?! 
From the beginning of the human history, all of those who claimed to be prophets were, in his worst assumption tortuous and devious and with his best assumption had psychological problems.