The kalam cosmological argument, developed by medieval Islamic theologians like Al-Ghazali, states: everything that begins to exist has a cause; the universe began to exist; therefore the universe has a cause. This cause must be uncaused, timeless, and immensely powerful — which Muslims identify as Allah.

Fitrah is the innate natural disposition every human is born with, inclining them toward recognizing God's existence and oneness (tawhid). The Quran (30:30) describes it as the original nature upon which God created humanity. Islamic theology holds that this awareness can become obscured by environment and upbringing but never fully erased.

Islam offers a multifaceted response: suffering serves as a test of faith (ibtila), a means of spiritual purification, and a consequence of human free will. God's wisdom (Al-Hakeem) encompasses purposes humans may not fully comprehend. Islam does not see evil as contradicting God's existence but as part of a purposeful moral framework.

The Quran issues a challenge in multiple verses (e.g., 2:23, 17:88) to produce even a single chapter like it. This challenge to the most eloquent Arabic speakers — and all subsequent generations — remains unmet. Islamic scholars cite this as evidence of the Quran's divine origin (ijaz al-Quran).

Burhan al-siddiqin is a philosophical argument formulated by Avicenna (Ibn Sina). It argues from the nature of existence itself: everything is either contingent (needs an external cause) or necessary (exists by its own essence). Since an infinite chain of contingent things is impossible, there must be a Necessary Existent (Wajib al-Wujud) — God.

Ilm al-kalam (Islamic theology) uses rational argumentation to defend core Islamic beliefs within the framework of revelation. Falsafa (Islamic philosophy) is rooted in Greek traditions and uses pure reason to investigate reality. Kalam scholars like Al-Ashari prioritized scripture supported by reason, while philosophers like Ibn Sina gave greater weight to philosophical demonstration.

Islamic scholars cite several categories of evidence: fulfilled prophecies about future events, the Quran itself as an inimitable miracle given to an illiterate man, his impeccable moral character testified to by opponents, the rapid transformation of Arabian society, and references in earlier scriptures.

The Quran was preserved through dual oral-written transmission. Thousands of companions memorized it during Muhammad's ﷺ lifetime. Written copies were compiled under Abu Bakr and standardized under Uthman within 20 years. Its mass-transmitted (mutawatir) status makes alteration effectively impossible, confirmed by modern manuscript discoveries.