They are the three Opponents (al-Adad)—may Allah curse them—meaning those who are of their progeny1 or have a connection2 to them; it is never permissible to grant them [the inner knowledge], for such a person would not be able to endure the cursing of his fathers and grandfathers, nor could he bear it, and thus he would become estranged from you.
As for "that which has been dedicated to other than Allah":
It refers to everyone who was titled "Commander of the Faithful" (Amir al-Mu'minin) from the Umayyads and the Abbasids. It is not permissible for anyone who has a lineage connected to them to be initiated into the Science of Divine Unity (Ilm al-Tawhid), for it is among the forbidden matters.
And [those killed by] strangling (al-munkhaniqah): It refers to the one who is drowned in the Outer Science (ilm al-zahir) and the beliefs of the Sunnis, such as those holding high positions in the Outer Science. It is impossible for such a person to profess the Science of Divine Unity (ilm al-tawhid)3 after being strangled by the outer sciences, as his flesh, blood, soul, intellect, and creed have been built upon them. For him, anyone who reveals to him anything of the Inner Science (ilm al-batin) is a disbeliever, whose blood is to be shed and whose killing is deemed permissible.