Evil has power -Ramchal

 Derech HaShem (Part 3) Regarding sorcery: And so in this way, just as He brought about a way for man to acquire emanation, understanding and the holy spirit in a supernatural way beyond the physical; so too was it necessary to bring about the opposite of this great good, such that man could bring down darkness, murkiness and a spirit of impurity in a supernatural way. And this is the matter of the impurities of sorcery and the seeking out of the dead from which the Torah distanced us. And its content is the bringing down of the influences of impurity and pollution by the mentioning of words under given conditions - which is really the greatest distancing from Him, may He be blessed, and truly the opposite of cleaving to Him. And the thing is brought down from those forces of evil that we mentioned in Part I, Chapter 5 (On the Spiritual Realm 8), upon which He, may He be blessed, decreed names through which given levels of impurity would be brought down in a supernatural way. Accordingly, supernatural acts can be done through them, like the acts of the Egyptian magicians and others, according to what is placed into their hand to act within the limits that were placed upon them. Likewise can they do acts like this through demons, according to what is given to them within the specific limits governing them. And so - within the measure allowed by their ability to act - the Master blessed be He, decreed that they push away the appointees over nature that preserve the matters of the world in their natural state and all of the angels that bring influences according to the arranged order. And about them, they, may their memory be blessed, said (Chullin 7b), "Keshafim (Sorcery)? It is [an acronym for] makhchishin pamalya shel ma'alah (they diminish the heavenly entourage)." However that is only within that measure and no more. And even within that measure, it is yet possible that they be pushed off by a force more powerful than them, and that their action be prevented by His decree, may He be blessed. And about this they said, "There is none like Him, and even in the case osorcery." And they explained that this is for [a person] who has great merit, such that they will save him and push off those who want to do bad to him, from the Heavens. And this is what is written, "Rabbi Ḥannina is different, because his merit is great."