Is this sentence grammatically correct-"Which they call evil, might be motivation for many"? [closed]

Original: Which they call evil, might be motivation for many”? (bad grammar)

"Which" is a relative pronoun that must be tied to a noun (a subject in this case, which is missing). Add "that" (pronoun) as a subject.

=> That [which they call evil] might be motivation for many.

(Essentially, "that might be motivation for many", where we have previously mentioned "evil".)