in proportion to what he neglects of these, as stated in the hadith:

“Whoever falls short in any of them has abandoned a share of Islam.”

When a person performs these deeds sincerely for Allah Most High, He rewards him for them. This can only occur when he affirms in his heart that there is no god worthy of worship except Allah and that Muhammad is the Messenger of Allah. He thus possesses this affirmation as a measure of faith. Yet this affirmation does not necessarily mean that he possesses certainty admitting no doubt, engages in jihad, or possesses the other qualities that distinguish a believer from a Muslim who is not a believer.

Many people who are Muslims both inwardly and outwardly possess this Islam, together with the faith it necessarily entails, but have not attained certainty and jihad. They are rewarded for their Islam and their general affirmation of the Messenger. They may not know that he brought a Book, that an angel came to him, or that he conveyed a particular teaching. If it has not reached them that the Messenger conveyed something, they are not required to affirm it in detail. Nevertheless, they must affirm that he is the Messenger of Allah and that he is truthful in everything he relates from Allah.

The faith that distinguishes the believer, however, includes detailed knowledge, reassurance, and certainty. It is thus distinct in its character and degree, both quantitatively and qualitatively. For those believers possess faith in Allah, His angels, His Books, His messengers, and the details of resurrection and divine decree that these Muslims do not know. Their hearts also possess a degree of certainty, steadfastness, and abiding conviction that these Muslims lack. Those are the true believers.

Every believer must necessarily be a Muslim, for faith necessarily entails deeds. But not every Muslim is a believer with faith in this unqualified sense, because