How can one restore faith in God and the feeling of inner peace after a negative psychological experience towards religion that led to weakening of faith and committing sins?

The existence of Allah the Almighty is the most truthful and evident of all realities. Everything we see around us points to Him. For either creatures brought themselves into existence, or they were created from nothing. Both possibilities are rationally and intuitively false. Thus, it is necessary that they have a Creator, a Disposer, a Wise One, and that is Allah, glory be to Him, as He Almighty said: ﴿Were they created by nothing? Or were they themselves the creators? Or did they create the heavens and the earth? Rather, they are not certain.﴾ [At-Tur: 35-36]. These verses were the reason for Jubayr ibn Mut'im's embracing of Islam. And the bad behavior of some Muslims is not an argument against Islam. Rather, one must refer to the Qur'an and the biography of the Prophet, peace be upon him, who was sent as a mercy to the worlds, possessed a great character, and confined the purpose of his mission to perfecting noble morals. So reflect upon the Qur'an and the biography of the Prophet, peace be upon him, to know the truth of Islam.