How can the mind and heart be purified from deviant and disbelief-related thoughts, and how can humility be restored, God's pleasure be sought after disobedience, and zeal for the religion be brought back?

The intrusive thoughts that come to a Muslim unintentionally, and which he neither entertains nor speaks of, but rather detests in his heart, do not harm him nor will he be held accountable for them. A Muslim can seek help in repelling them by strengthening his faith through reciting the Qur’an and contemplating its verses, sitting with righteous people, attending gatherings of knowledge, drawing closer to Allah through good deeds, and contemplating the universe to realize Allah’s existence and oneness. He should frequently recite the supplication: "O Turner of the hearts, keep my heart steadfast upon Your religion," and read Surah Al-Ikhlas and the two Mu'awwidhatayn (Surahs Al-Falaq and An-Nas), and regularly observe the morning and evening remembrances. For humility and tranquility come through striving in obedience to Allah and constant repentance to Him. Past distance from Allah and sins do no harm as long as repentance is sincere. Zeal for the religion is demonstrated by staying away from sins, hating them, fighting them, being patient in obedience to Allah, and adhering to the religion no matter how difficult the circumstances become.