Are the obsessive doubts about the validity of religion and whether the Quran has been distorted, and comparing Islam with Christianity, from the self or from Satan, and how can one get rid of them?

These intrusive thoughts do not harm the questioner as long as he dislikes and shuns them, and his dislike for them is proof of the sincerity of his faith. As for the proofs of the truth of the religion of Islam and that it is indeed the religion of Allah, they are numerous. Every proof that a Christian or a Jew can use to substantiate the truth of his religion, the application of that proof to the truth of our Prophet's prophethood, peace and blessings be upon him, is even more evident and clear. His truthfulness has been attested to by his numerous miracles, and by this Glorious Book (the Qur'an) which falsehood cannot approach, and by its challenge to the Arabs to produce its like, which they failed to do. Also, his foretelling of future events which occurred exactly as he prophesied, and his narration of past events in accordance with what was with the People of the Book, despite him being unlettered, and the soundness of what he called to and its conformity with reason and sound human nature. So let him praise Allah for this guidance and resist the whispers of Satan.