That this knowledge can arise with immediate certainty was disputed only by a few outliers among the speculative theologians. Many of them, however, disputed whether this actually occurs, maintaining that most people acquire it only through rational inquiry. Most people disagreed with them, saying that, on the contrary, this knowledge is innate and immediately certain for most people.
[Ibn al-Zāghūnī’s Discussion of the Obligation to Engage in Rational Inquiry]
Ibn al-Zāghūnī is among those who hold that rational inquiry is obligatory and that this knowledge can be acquired only through it. He even says:
“Section: If someone says, ‘I believe that the world came into existence, that Allah is One, and that the religion is true, and I acknowledge prophethood—not through rational inquiry or inference, nor through examining an argument or proof, but by accepting the views of others on these matters, or by some other means that does not lead to firmly established knowledge through examining an argument or proof, so that inference culminates in true knowledge,’ then this person is not a believer. We do not judge him to be a believer before Allah, nor is he rewarded for this faith. Rather, he is punished and blamed for neglecting what he was commanded to do: acquire knowledge of Allah and of the truth of the religion and prophethood, and examine that which leads to certain knowledge of these matters.”
He says:
“One group says: He is a believer in our judgment and before Allah, provided his beliefs accord with divine oneness, prophethood, and the truths he is required to believe concerning religious knowledge, whether or not he is capable of attaining this through a method whose proofs bring him to certainty.”
He says:
“Another group says: He is outwardly a believer in our judgment, but we do not know whether he is a believer before Allah or not.
“Another group says: We judge them to be believers so long as nothing contrary to this occurs to them, such as likening Allah to creation, spatial location, the denial of prophethood, and the occurrence of