What is the reason for the takfiri thoughts and doubts that plague me during the month of Ramadan, and how can I overcome them and return to the sweetness of faith?

One must seek refuge in Allah from Satan and resist the whispers (waswasa), for they do no harm as long as the heart rejects them; indeed, detesting them is a clear sign of faith. These whispers are from Satan, so one must turn away from them and engage in obedience and the remembrance of Allah, while maintaining moderation in acts of worship and balancing various rights.