Is man's innate disposition a separate authority for setting rules? If a person commits a major act of disbelief, will the person be saved from being judged as a disbeliever because he is naturally disposed to believe in the Oneness of Allaah?

All perfect praise be to Allaah, The Lord of the Worlds.  I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Man's innate disposition is not enough to guide people to the right path, rather Islam complements its role and details rulings that man’s innate disposition cannot reach independently. To clarify, the relationship between one's innate disposition and the Sharee‘ah (Islamic law) is like the relationship between the eye and light. Like eyes that cannot see in an absence of light, man’s innate disposition is not enough in the absence of a revealed Sharee‘ah.

Shaykh Al- Islam Ibn Taymiyyah mentioned that the revealed Sharee‘ah complements man's innate disposition, since a person’s disposition recognizes matters in general, while the Sharee‘ah deals with details and explains and attests to what the innate self cannot do alone. He added that Allaah The Almighty created His slaves’ disposition towards the truth and the Messengers were sent to complement and confirm the role of man's innate disposition, not to transform or change it.

Actually, the person who commits Shirk (polytheism) or disbelief does swerve from this innate disposition, because it does not accept anything but Tawheed (monotheism). On the other hand, this does not mean that people are born Muslims and adhere to the rulings of Islam. Instead, it implies – according to Ibn Taymiyyah – that the individual is born sound and free from all false beliefs and ready to accept correct ones.

Therefore, the person who commits Shirk or disbelief will be corrupting their innate disposition, because it will be exposed to evil desires and malicious allegations that screen it from the truth. Ibn Taymiyyah also likened man's innate disposition and the truth to vision and the sun: every individual should be able to see sunshine if there is no barrier between them. Similarly, false and passing beliefs such as Christianity, Judaism or Magianism, are like a barrier that prevents the eyes from seeing the sun. Also, any individual with normal taste loves sweetness, unless its nature is contaminated and turns into bitterness. Being born with this innate disposition does not mean that a baby will embrace Islam with its mind, as Allaah The Almighty brings us from our mothers' wombs unaware of anything. Rather, a baby is born with a sound heart that accepts and wants the truth, i.e., Islam, to which the person will adhere if exposed to certain conditions. This scientific evidence implies that Islam, in case there is no impediment, is the innate disposition with which Allaah The Almighty has created people.

Allaah Knows best.