[3]. I.e., after having been convinced by such evidence. Everyone who believes that there is no god except Allāh and that Muhammad is His Messenger, is safe. Only by belief in Allāh and Mohammad as His last messenger can we receive salvation. Not only knowledge about Allāh, but deep, sincere faith, demonstrated by following the Qur’an and the teachings of prophet Muhammad, God's last and final messenger.
[4]. The Prophet Muhammad ﷺ said: “Allāh would not deal a believer unjustly even (as to) a single good deed. He will be given for it in this worldly life and rewarded for it in the Hereafter. But the denier will be fed the rewards of his good deeds in this worldly life until when he comes upon the Hereafter there will be nothing for him to be rewarded for.”
[5]. I.e , The Qur’an.