I believe English is actually one of the only ones where cult has a negative connotation, and where sect does not. French, Italian, Spanish, Portuguese, German, Dutch, Polish, Romanian, Swedish, Russian - all of these use "cult" to mean any religious group, even in official language ("the Catholic cult"), and all use "sect" to mean "a fringe, possibly dangerous, religious or quasi-religious group" ("the members of that sect that poisoned themselves").