Is human nature an independent argument for the revelation of rulings, such that one who commits major disbelief is not considered a disbeliever on the grounds that he is naturally inclined to the Oneness of God?

Innate disposition (fitra) alone is not sufficient to guide people, for the Sharia complements the fitra and details rulings that the fitra cannot independently establish. The fitra understands matters in a general way, while the Sharia elaborates and clarifies them. Allah created His servants with an innate disposition towards truth, and the messengers were sent to perfect and affirm this fitra, not to change it. Whoever falls into polytheism (shirk) or disbelief (kufr) has deviated from the sound fitra that accepts monotheism. The fitra at birth is "soundness from false beliefs and acceptance of correct doctrines." If the fitra becomes corrupted by doubts (shubuhat) and desires (shahawat), the truth becomes veiled from it. A sound fitra perceives the truth clearly, unless it is obscured by false beliefs, just as a veil obstructs the sun's light from the eye.