Many people are aware that the title for this post comes from a statement made by the Venerable John Henry Cardinal Newman, convert to Catholicism from Anglicanism. The sentiment being expressed is that you will not find any reasonable historical testimony in the Early Church Fathers (ECFs) for uniquely "Protestant doctrines." While Protestants might accept various early church teachings, such as the Divinity of Christ, in virtually every case Catholics accept that teaching as well. But the reverse is not true: there are many "Catholic teachings" found in the ECFs that Protestants not only do not accept, they contradict central dogmas of Protestantism (e.g. Sola Fide).
A popular form of 'damage control' Protestants use in response to this damning realization is to turn around and point to a few doctrines they believe don't have sufficient historical testimony and use that to say the Catholic Church must be false. This approach fails on two main grounds: (a) it doesn't get the Protestant out of the fact they are embracing a radically ahistorical Christian outlook, and (b) when looking at the 'big picture', that is all doctrines, the overall testimony of the ECFs shows the early Church to be very Catholic. Thus, for a Protestant to be fixated on something like the historical testimony for the Immaculate Conception, claiming it was not taught, and use that as their major criteria for rejecting/refuting Catholicism is a distortion of the big picture. No Catholic claims each and every doctrine has the same level of historical testimony, or even that some doctrines are not as well attested to as others; that doesn't mean we cannot form a reasonably solid conclusion on which Christian group today is best candidate for "One, Holy, Catholic, and Apostolic Church".
Consider the following list of doctrines I quickly put together (there are others that I've not included), which I believe far, far more strongly testifies the ECFs were Catholic than Protestant:
Almost no ECF testimony for Eternal Security, Imputation of Christ’s Active Obedience, The Father pouring out His Wrath on the Son at the Cross, Receiving Christ’s Righteousness by Faith, categorizing Justification as Forensic, etc.
On the flip side, there is clear ECF testimony for losing salvation by sin, the reality of Free Will, Justification via internal transformation, salvation by ‘works’ (i.e. entering Heaven based on your good or bad works), saving grace being available to all men, church imposed penances for falling into sin, etc (All of these latter concepts are very Catholic, but the former ones Protestants teach are essential for holding to the "true Gospel".)
I don’t know of a single ECF who espoused the Protestant Canon or who taught we go around determining canonicity the way the Westminster Confession teaches. There are ECFs who taught the Catholic Canon, and the rest who had a ‘mixed canon’ lean Catholic because they never totally excluded the "Deutero-Canonical" books. (Protestantism teaches the Church cannot even function without the proper canon of Scripture.)
There is clear Patristic testimony for the three-fold (i.e. distinct) offices of Deacon, Priest, and Bishop. Clear evidence for the binding authority of Ecumenical Councils, for Apostolic Succession (rather than self-appointment), a hierarchy among bishops (with strong examples of the Bishop of Rome being at the top of the list), for the Church and/or diocese having the power to impose disciplinary practices, and encouragement for things such as celibacy and the ascetic lifestyle. (All of these are uniquely Catholic but anathema to Protestant ears.)
There is clear evidence of the Mass being seen as a Sacrifice, the Bread and Wine being seen as really Christ (even if you want to dispute transubstantiation), Sunday being the normative day of worship (not any day you feel like it), and a structured Liturgy for each region. Further, there are prayers for the dead, veneration of Saint’s Relics, use of images, etc. Clear veneration of Mary as “Mother of God” and Perpetual Virgin, Infant Baptism, Baptismal Regeneration (including interpreting John 3:5 and Titus 3:5 as proof), and clear testimony against divorce and remarriage. (As with the other teachings, these sound much more Catholic than Protestant, with many of them being anathema to Protestant ears.)
The above list of teachings is a good example of what it means to look at the 'big picture', and this is how one should approach any Protestant challenge on the subject.
Now, to take that whole list and go trumpeting around a few doctrines and why this or that ECF didn't teach the doctrine - as if that’s the ‘big picture’ - is a distortion of the situation. On any such ‘disputed’ items, what a Protestant might consider weak evidence can be seen as sufficient evidence by Catholics in light of the strong testimony for the ‘big picture’ coming off far more Catholic than Protestant.
If a Protestant wants to respond to the overwhelming fact the ECFs come off sounding far, far more Catholic than Protestant by saying “so what,” that’s their right, but it’s also an admission of a radical ahistorical paradigm their ‘church’ is embracing. This radically ahistorical paradigm is where the concept of “to be deep in history is to cease to be Protestant” comes from.