Jesus is telling his Followers not to be like the Sadducees and Pharisees who seek the "first places":Everything they do is done to impress people. They enlarge their tefillins and lengthen their tassels. They like the most important place at meals, and the chairs of honor in their synagogues, and to be cheered on the street, and to be called by people "Rabbi." You, however, must not be addressed as "Rabbi," since you have only one Teacher, and you are brothers to each other. Do not address any man on earth as father, since you have only one Father, and he is in heaven. And you must not be addressed as leaders, since you have only one Leader, the Messiah. The greater among you will be your servant. For whoever boosts himself up will be lowered, and whoever lowers himself down will be boosted up. (Mt. 23.5-12)What could be more against this teaching than popes who adopt the title "Holy Father"?
Wills is exactly right. While the "call no man father" command does not mean we can never in any way refer to other men as fathers, the kind of behavior it does prohibit is precisely the behavior of Roman Catholics, in elevating a single man above all others.
Wills continues (p. 12):
Thus the post-Gospel literature of the Jesus movement introduces people in administrative roles--Servants, Elders, Overseers. These are not charisms bestowed by the Spirit, but offices to which people are appointed by their fellow human beings--and once more the priesthood is missing from the list.
Wills is right again. He goes on to explain what "Servants" (deacons), "Elders" (presbyters), and "Overseers" (bishops). Wills notes that Paul, in his letters, uses the plural term "episkopoi" once (at Philippians 1:1). Luke, in Acts, similarly reports Paul as using the plural term.
In Philippians 1:1, Paul and Timothy greet, as Wills explains (p. 13) "(1) God's people, (2) the Overseers, (3) the Servants." These are the overseers, plural, for the church at Philippi. Similarly, at Acts 20:28, Paul speaks to the overseers, again plural, of the church at Ephesus.
In two other cases, the singular form is used, but even there the occurs in conjunction with elders (presbyteroi plural) or board of elders (presbyterion - which implies a plurality of people).
I would, naturally, disagree with Wills' suggestion (p. 14) that these possibly later singular usages point towards a development of the monarchical episcopate, such as argued-for by the letters of Ignatius. Nevertheless, Wills historical points that Paul's usage suggests that the leadership of the church is not a leadership by one, but by plurality of more or less equals.
Furthermore, Wills is right in noting the fundamental distinction and discontinuity between the apostles (whose gift was a charism of the Holy Spirit) and the elders/bishops that followed them, whose appointment was by men, even those who were appointed by the apostles themselves. Even though these offices of deacon and elder are divinely authorized offices, they are divinely authorized in a different way from the apostolic office.
Significantly - both for Wills and us - none of this pointed to a priest or high priest over the local assembly. The apostles themselves were not priests, and they did not even set up a human office of priest.