What is the ruling on reading books by sorcerers (spirituality) out of curiosity, without believing in them, and then affirming the Oneness of God, praising Him, and disavowing their authors?

It is not permissible for a Muslim to read books on magic, charlatanism, and sorcery, and the prohibition thereof is emphasized. If the Shari'ah has forbidden looking into the books of the People of the Book without necessity, then books of magic are even more deserving of prohibition. However, an exception is made for that which contains a legitimate Shari'ah benefit, such as when a person of profound knowledge reads them for a legitimate Shari'ah purpose, like establishing the truth or refuting falsehood. Instead, a Muslim should direct their efforts towards studying books of Islamic knowledge.