One benefit of reading the primary sources for oneself is that the actual writings are seen and read in context. In my Ancient Church course taught by Dr. R. Scott Clark, we have to read a sampling of the primary patristic texts (translated into English of course). It constantly amazes me how orthodox the early Church Father generally are, although of course they are not always orthodox on everything. The nascent Covenant Theology embraced by the apologists Justin Martyr and Ireneaus of Lyons is one such example. While it is anachronistic to read modern theological issues back into the Church Father, the Church Fathers did show awareness of some of these topics and laid the foundation for later theological development along these lines.
In his famous work On the Incarnation, Athanasius (the famous 4th century bishop who defended the Nicene faith against the Arian heretics) gave a presentation of salvation that generally could be said by any Evangelical. In his discussion of the Incarnation, Athanasius grounded the incarnation as being integral to God's solution to the problem caused by Man's sin. As it was stated:
6. For this cause, then, death having gained upon men, and corruption abiding upon them, the race of man was perishing; the rational man made in God's image was disappearing, and the handiwork of God was in process of dissolution. For death, as I have said above, gained from that time forth a legal hold over us, and it was impossible to evade the law, since it had been laid down by God because of the transgression, ... ... For it were not worthy of God's goodness that the things he had made should waste away, because of the deceit practiced on men by the devil. ... So as the rational creatures were wasting and such works in course of ruin, what was God in his goodness to do? Suffer corruption to prevail against them and death to hold them false? And where were the profit of their having been made, to begin with? For better were they not made then, once made, left to neglect and ruin. For neglect reveals weakness, and not goodness on God's part ...
7. But just as this consequence must needs hold, so, too, on the other side the just claims of God lie against it: that God should appear true to the law he had laid down concerning death. For it were monstrous for God, the father of truth, to appear a liar for our profit and preservation. So here, once more, what possible course was God to take? To demand repentance of men for their transgression? ... But repentance would, firstly, fail to guard the just claim of God ... nor, secondly, does repentance call man back from what is their nature ...
8. For this purpose, then, the incorporeal and incorruptible and immaterial Word of God comes to our realm, howbeit he was not far from us before. For no part of creation is left void of him... But he comes in condescension to show loving-kindness upon us, and to visit us. ... he took pity on our race, and had mercy under penalty of death, and condescended to our corruption, and ... he takes upon himself a body, and that of no different sort from ours. ... And thus taking from our bodies one of life nature, because all were under penalty of the corruption of death he gave it over to death in the stead of all, and offered it to the Father — doing this, moreover, of his loving-kindness, to the end that, firstly, all being held to have died in him, the law involving the ruin of men might be undone ... and that, secondly, he might turn them from death by the appropriation of his body and by the grace of the resurrection, banishing death from them like straw from the fire.
9. For the Word, perceiving that not otherwise could the corruption of men be undone save by death as a necessary condition, while it was impossible for the Word to suffer death, being immortal, and Son of the Father; to this end he takes to himself a body capable of death, that it, by partaking of the Word who is above all, might be worthy to die in the stead of all ... Whence, by offering unto death the body he himself had taken, as an offering and sacrifice free from any stain, straightaway he put away death from all his peers by the offering of an equivalent. ...
— Athanasius, On the Incarnation. In Edward Rochie Hardy, ed., The Library of Christian Classics Vol. III: Christology of the Later Fathers (Philadelphia: The Westinster Press, 1954), pp. 60-63
In this quote, Athanasius grounded the necessity of the incarnation in that Christ came into our world in order to die for us on our behalf. The death he died was paid to God the Father in order to free us from the "law involving the ruin of man" or the sentence of death against us. Athanasiu explicitly denied repentance was sufficient for salvation since repentance alone cannot change the nature of Man. The only way to do so is for Christ to be incarnated for us.
Now, is Athanasius always right? No. That is why we are called Protestants. Like Calvin, we appreciate the Church Fathers while recognizing the normative authority of Scripture Alone, and critique them when they are not following Scripture. For example, we can critique Athanasius' argument for the necessity of God having to save Man. We can discern the compromises the Church Fathers made with Greek philosophy especially Platonism, and those have to be rejected. Nevertheless, the Church Fathers were genrally orthodox and wrote in a generally biblical framework. You wouldn't for example read any of the Church Fathers and think that their doctrines bear any resemblances with the teachings of Roman Catholicism. Rome's developmental view of doctrine surely works wonders in postulating an apostolic succession from the early Church Fathers to Vatican II and beyond.
Athanasius' work On the Incarnation is truly a good work, which should be read by all Christians. I would venture to say that Athanasius was more evangelical than many so-called Evangelicals today, suely more an indictment against the modern church than praise for Athanasius' theology itself.