Why believe the Creator is involved (deism)?

How scholars have understood it

What deism is. Encyclopaedia Britannica defines deism as "natural religion": accepting religious knowledge "that is inborn in every person or that can be acquired by the use of reason", and rejecting religious knowledge acquired through "revelation or the teaching of any church". It differs from atheism (no God at all) and from Islamic theism, in which God creates, sustains every moment of existence, and speaks through prophets.

The kalam argument from grace (luṭf). Kalam is Islamic rational theology. The Muʿtazila (an early rationalist school) and later Shiʿi (Imami) theologians held that luṭf — God's act that "motivates a person to obedience and keeps him away from disobedience" — is required of God, and they counted both moral obligation (taklīf) and the sending of prophets (irsāl al-rusul) as instances of it. Their argument ran: sending prophets is an act of luṭf; luṭf is required of God; so sending prophets is required of God. Shiʿi theologians such as Shaykh al-Mufid and Naṣīr al-Dīn al-Ṭūsī (in Tajrīd al-Iʿtiqād) developed this (Meghjee).

The Ashʿari answer: prophecy is a gift, not a debt. The Ashʿaris, the largest Sunni school of theology, rejected the claim that anything is required of God, since nothing outside God governs His acts. For them God was not obliged to send prophets; He chose to. Meghjee cites al-Ghazali's al-Iqtiṣād fī al-Iʿtiqād for this view. Both sides agreed that prophets were in fact sent; they disagreed on whether reason can show that they had to be.

Al-Ghazali: from inherited belief to certainty. Al-Ghazali (d. 1111), the most influential Sunni theologian of his age, describes in al-Munqidh min al-Dalal (Deliverance from Error) how his search began: "I saw that Christian youths always grew up to be Christians, Jewish youths to be Jews and Muslim youths to be Muslims", and he recalled the hadith that everyone is born with "a sound nature" (Watt, section I). He went through a period of radical doubt lasting "almost two months", which ended not by argument but by "a light which God most high cast into my breast" (section II). On prophecy, he argues that you know a prophet the way you know that someone is a physician or a lawyer: from his conduct and his work. "Certainty can only be reached by acquaintance with his conduct", he writes; seek certainty "about the prophetic office, and not from the transformation of a rod into a serpent". By testing the Prophet's teaching in many instances, "you will arrive at a necessary knowledge beyond all doubt" (Watt, passage before section V). This is a cumulative argument: no single sign settles it, but many together can.

Nursi: the alternatives to a Maker. Said Nursi (d. 1960), the Turkish scholar whose Risale-i Nur is widely read, argues that when we see a living thing we have only a few explanations: it formed itself, causes produced it, nature required it, or it was made. Against self-formation he writes that "each particle or atom forming your body would have to have an eye to see your whole body". Against blind causes: "How can that which is deaf, blind, and unconscious bestow hearing, sight, and consciousness on something else?" Against "nature": "Nature cannot create because it is something supposed to exist" — for him "nature" is a name for an order, not a maker. His conclusion is that each creature points to one conscious Maker. Nursi's word inayet (Arabic ʿināya), "care" or "providence", names what he sees in that order: not only design but attention to each thing's needs. His argument reaches a caring Maker; it does not by itself reach revelation, which he defends elsewhere.