a trace like the mark of a blister, as when you roll an ember over your foot and see a swelling, yet there is nothing inside it.”

The answer is:

The removal of trust and faith is not the same as the removal of knowledge. A person may be granted faith while lacking knowledge. Such faith may be taken from his heart, as happened to the faith of the Children of Israel when they saw the calf. But whoever has been granted knowledge together with faith will not have that knowledge taken from his heart. Such a person never apostatizes from Islam, unlike someone who merely possesses the Quran or faith alone, for these may be taken away. This is what actually occurs.

Yet we most often find apostasy among those who possess the Quran without knowledge and faith, or those who possess faith without knowledge and the Quran. As for someone who has been granted the Quran and faith, and thereby acquired knowledge, this will not be taken from his heart. And Allah knows best.