Now I will examine the Fathers, to see what their position is on the matter. As a whole, the Fathers are not concerned with addressing this issue in detail. Nevertheless, when they do speak of it, they generally put some qualifications on the statement that “there is no salvation outside the Church.” Sometimes it is clear what they mean, other times not so clear. In some cases it is quite clear that they allow for implicit faith, in other cases not so clear. Let us look at the texts:
St. Justin Martyr, First Apology, 46: "We have been taught that Christ is the first-begotten of God, and we have declared him to be the reason in which all mankind partakes [John 1:9] . Those, therefore, who lived according to reason were really Christians, even though they were thought to be atheists, such as, among the Greeks, Socrates, Heraclitus, and others like them. . . . Those who lived before Christ but did not live according to reason were wicked men, and enemies of Christ, and murderers of those who did live according to reason, whereas those who lived then or who live now according to reason are Christians.”
St. Justin clearly admits as a “Christian” anyone who lives at any time according to reason, even those outside the visible Church. The discussion comes up in the context of answering how people before the coming of Christ were still responsible for their actions, because they did not know Christ. His response is to say that those who lived according to reason were really Christians, while those who lived against reason were wicked and hostile to Christ. And notice what he says, "whereas those who lived then or WHO LIVE NOW according to reason are Christians." It is quite clear that while the argument arose in the context of salvation before Christ, he nevertheless applies precisely the same argument now: i.e., those who do not know of Christ now, but live according to reason are really Christians. Thus, since those before Christ were Christians and could be saved by an implicit faith in Christ, likewise those after Christ are Christians and can be saved by an implicit faith in Christ.
St. Irenaeus, Against Heresies, BK IV, Ch, 22, “It was not merely for those who believed in Him in the time of Tiberius Caesar that Christ came, nor did the Father exercise His providence for the men only who are now alive, but for all men altogether, who from the beginning, according to their capacity, in their generation have both feared and loved God, and practiced justice and piety towards their neighbors, and have earnestly desired to see Christ, and to hear His voice. Wherefore He shall, at His second coming, first rouse from their sleep all persons of this description, and shall raise them up, as well as the rest who shall be judged, and give them a place in His kingdom.”
St. Irenaeus says that all will be saved who have feared and loved God, practiced justice and piety towards their neighbors, and have earnestly desired to see Christ, and to hear His voice. Notice this: All those who have done this “according to their capacity,” will be saved. Now, those who have not heard of Christ only have the capacity to have an implicit faith in him; hence that is sufficient for their salvation. If someone were to object that this is not the intention of St. Irenaeus, contra this is the fact that he explicitly applies this text to those before Christ, who were not able to believe in Christ explicitly, but only implicitly. At the same time, it is clear that he is not limiting this application to those before Christ, since he says that when Christ comes again, he will grant salvation to “all men together, who from the beginning, etc.”