What is the ruling on reading books available for free online, from disbelievers or Muslims, knowing that they do not consent to this and that people circulate them?

If the authors of books and websites stipulate the prohibition of copying and circulation without prior permission, then it is not permissible to circulate them, because it infringes upon their rights. However, if they do not stipulate this, or if it is known that they do not prohibit it, then there is no harm. An exception to this prohibition is if the books belong to individuals hostile to Muslims, in which case they may be examined for cautionary purposes. The right of publishing and distribution is among the legitimate rights that must be respected.