“Many scientists and doctors have been doubters of religious dogma, including physicist Galileo, the Jewish theorist and doctor Maimonides, the Muslim philosopher and doctor Abu Bakr al-Razi, and the physicist Marie Curie.”

— Jennifer Hecht (2004), Doubt: a History [1]

“Al-Razi is the greatest non-conformist in the whole history of Islam; the most free-thinking of the major philosophers of Islam; the lest orthodox and the most iconoclast; perhaps the single figure most frequently denounced and disapproved as a heretic in the subsequent history of Islamic thought. His doctrine emerges as irreconcilable with any kind of Islam, however open-minded.”

— Jennifer Hecht (2004), aggregate quote of views, via citation of Sarah Stroumsa (1999), on Al-Razi [2]

“As a result of 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 …”

— Zakariya Razi (c.910) Source; cited by The Encyclopedia of Islam (1938) as the “most violent polemic against religion in the course of the middle ages.” [3]

“If the people of this religion are asked about the proof of the soundness of their religion, they flare up, get angry and spill blood of whoever confronts them with this question. They forbid rational speculation, and strive to kill their adversaries. This is why the truth became thoroughly silenced and concealed.”

— Zakariya Razi (c.910) [2]

“You claim that the evidentiary miracle is present and available, namely, the Quran. You say: ‘whoever denies it, let them produce a similar one’. Indeed, we shall produce a thousand similar, form the works of the rhetoricians, eloquent speakers and valiant poets, which are more appropriately phrased and stated 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 if full of contradictions and does not contain any useful information or explanation. Then you say: ‘produce something like it’?!”

— Zakariya Razi (c.910) [2]

“Jesus claimed that he was the son of god, while Moses claimed that god had no son, and Muhammad claimed that Jesus was created like the rest of humanity. Moreover, 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.”

— Zakariya Razi (c.910) [2]

“No soul can be purged from the turbidity of this world and escape to the next, except by contemplating philosophy. If a person contemplates philosophy and comprehends anything, be it ever so small, his soul is purged from this turbidity and is saved.”

— Zakariya Razi (c.910) [2]