Does G-d make use of evil spirits to do bad things?
Both good and evil are G-d's creations; see Isaiah 45:7. He can certainly make use of evil spirits, for example to smite the Egyptian firstborn (Ex. 11:23). The "evil spirits" in Judges 9:23 and 1 Sam.15:14 were bad states of mind (anger, depression); G-d created man to be capable of both good and evil (see Gen.6:5 and 8:20).
There is a range of Jewish views about evil spirits; Maimonides
apparently believed that they are subjective.
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