Does the seeker feel distress and doubt in his religion and suffer from whispers after repenting from sins, and is there a way to mend his heart and return to his former state of faith?

Abandoning forbidden acts is a tremendous step on the path back to Allah. If a believer is touched by an impulse from Satan, he remembers what Allah has enjoined upon him, becomes insightful, and seeks Allah's forgiveness. As for the brethren of devils, they do not fall short in doing evil.

Satan strives to discourage those who repent and to cast them into despair and despondency. Man is in a continuous battle against his devil and his own self. He must be patient in adversity, grateful in prosperity, and seek forgiveness when committing a sin.

Multiplying acts of obedience and good deeds purifies sins, sanctifies the soul, and firmly establishes faith, for good deeds erase bad deeds.