How can one overcome the whispers of the self that may include doubts about faith and fear of polytheism (shirk)?

The thoughts and whispers that cross one's mind are not within a person's control, and they will not be held accountable for them as long as they do not act upon them or speak them, according to the saying of the Prophet, peace and blessings be upon him: "Indeed, Allah has overlooked for my Ummah what they whisper to themselves, as long as they do not speak of it or act upon it."

What comes to mind regarding matters of creed is a sign of faith, according to the saying of the Prophet, peace and blessings be upon him: "That is pure faith."

Therefore, it is recommended to frequently remember Allah, occupy oneself with what is beneficial, avoid dwelling on inner whispers, and say, "I believe in Allah," for whoever experiences such thoughts.