What is the cause of whispers (waswas) and doubts about Islam, and what is the cure for them for a person with extensive religious knowledge and a high critical sense, who is facing atheistic and anti-Islamic thoughts?

The questioner is advised to fear Allah, increase in supplication and humble entreaty so that Allah may remove the veil from him and he may see the light. He should ponder over the verses of Allah in the universe and in the Quran, and consider the greatness of the religion of Islam compared to others. He is also advised to seek help from pious scholars in resolving difficulties, to keep company with the righteous, and to attend gatherings of knowledge and remembrance. It is pointed out that the cause of whisperings (waswas) may be a lack of mastery of Islamic teachings. He is warned against reading books tainted with ideas contrary to Islam, except for those who are proficient and able to distinguish between truth and falsehood and refute misconceptions.