First off, let me state that I acknowledge that the Pope has doctrinal and spiritual authority over the Catholic Church, and that in the eyes of the Catholic Church this authority covers the entire Church as expressed in
CCC 882. However, his authority over the Christian churches that are in imperfect communion with the Holy Catholic Church is just that… functionally imperfect.
Allow me to give an example to show what I mean. The relationship between the Pope and the non Catholic Christian Churches is similar to the relationship between Hu Jintao (the General Secretary of the Communist Party of China as well as its President) and the Republic of China (also known as Taiwan). The Pope and Hu Jintao are able to exert authority over the non-Catholic Christian Churches and Taiwan respectively in similar manners. First, let me start by saying that both the Catholic Church and the non Catholic Churches call each others Brothers and Sisters in Christ (
CCC 818). Similarly, the Peoples Republic of China (PRC) and the Republic of China (ROC) acknowledge there is but one China that they are both a part of.
Also, the Pope had doctrinal authority over the Catholic Church but not over the non Catholic Churches. In the Same way, Hu Jintao has policy control over the the PRC but not over the ROC. Even though both the PRC and ROC state that there is but one China, Hu Jintao can not set the policy of the ROC. The ROC does not recognize the leadership of Hu Jintao over their portion of the one China. Therefore his decrees and policies are not enacted on the ROC which makes his authority incomplete. In the same way, the Pope does not have functional authority over the non-Catholic Christian Churches because they do not acknowledge the doctrinal decrees of the Pope.
In summary, the authority of the Pope over the non-Catholic Christian Churches is imperfect because they choose not to acknowledge the doctrinal decrees of the Pope. Even though the pope does not have functional authority over the non-Catholic Christian Churches, we still often look to him as an example of Christian leadership.
I hope this has helped examine the functional authority of the Pope from the eyes of a protestant.
PS: This post was not addressing spiritual authority of the Pope. Rather, its
only purpose was to address the ability of the Pope to functionally exert his authority.