Unfortunately, too many people feel the point of CRM skills is to share authority. It is not
I agree. What could be shared are the leadership skills. Also as good leader the FO should display good followership skills.
I hope this makes sense.
To keep it simple. The captain has got the authority, but both pilots do have the same opportunities to make inputs that improve safety and efficiency. The FO should assist the CP as much as he can while making valuable obervations.