“There is no such thing as the Protestant Church, therefore it is impossible to have any type of unity. “
All believers of all time have unity in the Person of Christ and His Gospel of Grace.
Protestants are not members of the Catholic Church. Christ established a very visible church, with a structure, and heirarchy consisting of bishops and priests and deacons. All appointed with Holy Orders. Protestants are not members.
Protestants are no more members of the Catholic Church than they are the Orthodox Church. Protestantism is a false religion.