What is the ruling on one who suffers from weakness of faith, lack of fear of Allah, mockery of religion, and doubt in religions and admonitory stories?

You must repel the whispers of atheism by contemplating the Qur'an, reciting it, and understanding its verses, along with frequent remembrance of Allah (dhikr) and supplication (du'a). You should also read specialized books refuting atheistic claims, such as: "Physics and the Existence of the Creator" by Ja'far Sheikh Idris, "God Manifests in the Age of Science," "Islam Challenges" by Wahiduddin Khan, and "A Struggle with Atheists to the Bone" by Abd al-Rahman al-Midani. It is important to differentiate between doubting Allah Almighty and mere whisperings (waswasa), as what occurs might be waswasa and not doubt.