بُنِيَ الإِسْلَامُ عَلَى خَمْسٍ
Islam is built upon five.
The language of foundations emphasizes the essential practical structure of Muslim religious life. It does not, by itself, establish that inward assent is irrelevant or that every failure to perform a pillar necessarily removes faith.
A description of a structure by its foundations does not exhaust every feature of that structure. In the same way, listing Islam's pillars and defining the theological essence of faith answer related but different questions. The scriptural evidence must be read with this difference in mind.