وَمِنَ ٱلنَّاسِ مَن يَقُولُ ءَامَنَّا بِٱللَّهِ فَإِذَآ أُوذِىَ فِى ٱللَّهِ جَعَلَ فِتْنَةَ ٱلنَّاسِ كَعَذَابِ ٱللَّهِ
"There are people who say, 'We have believed in God'; but when such a one is made to suffer for God's sake, he counts the affliction people inflict as though it were the punishment of God."
I record this as my own reading, and its ground is the particle of comparison (kāf): the verse diagnoses not the presence of fear but a slippage of scale. A pressure that is temporary and limited is weighed as having the same weight as what is lasting and unlimited. The person is not denying — he is using the wrong balance.
فِتْنَة — root ف-ت-ن: to melt gold in fire in order to test its purity. The root was treated at al-Burūj and at al-Baqara 2/191. I do not repeat it here.
The place of the root in this sūra is worth recording: in the second verse it had occurred as lā yuftanūn (they will not be tested); here the same root is used for the affliction inflicted by people. That is, trial does not remain an abstract concept — it is named as a concrete pressure.