A beautiful early Christian writing, the Letter to Digonetus, has been dated at 100-150 A.D. and is sometimes called the earliest example of Christian apologetics written to a non-Christian audience (some additional background is given in the Introduction at CCEL.org). Its author is unknown.
Here are a few excerpts that might be of interest to LDS readers. Chapter 6, for example, discusses our dual nature, explaining that we have an immortal spirit contained within our physical body. A simple point, but one that has been the subject of much confusion among some in modern Christianity.
Chapter 6. To put it simply: What the soul is in the body, that Christians are in the world. 2 The soul is dispersed through all the members of the body, and Christians are scattered through all the cities of the world. 3 The soul dwells in the body, but does not belong to the body, and Christians dwell in the world, but do not belong to the world. 4 The soul, which is invisible, is kept under guard in the visible body; in the same way, Christians are recognised when they are in the world, but their religion remains unseen. . . . 7 The soul is shut up in the body, and yet itself holds the body together; while Christians are restrained in the world as in a prison, and yet themselves hold the world together. 8 The soul, which is immortal, is housed in a mortal dwelling; while Christians are settled among corruptible things, to wait for the incorruptibility that will be theirs in heaven. 9 The soul, when faring badly as to food and drink, grows better; so too Christians, when punished, day by day increase more and more.
Chapter 7, at least as I read it, speaks of the role of Christ and His relationship to the Father in terms very similar to the nuances of LDS theology. Christ, though (implicitly) a separate being, is like the Father and is God also, but under the direction of the Father, who had Christ act as the Creator and who sent Him into the world.
2 On the contrary, it was really the Ruler of all, the Creator of all, the invisible God himself, who from heaven established the truth and the holy, incomprehensible word among men, and fixed it firmly in their hearts. Nor, as one might suppose, did he do this by sending to men some subordinate—an angel, or principality, or one of those who administer earthly affairs, or perhaps one of those to whom the government of things in heaven is entrusted. Rather, he sent the Designer and Maker of the universe himself, by whom he created the heavens and confined the sea within its own bounds—him whose hidden purposes all the elements of the world faithfully carry out, him from whom the sun has received the measure of the daily rounds that it must keep, him whom the moon obeys when he commands her to shine by night, and whom the stars obey as they follow the course of the moon. He sent him by whom all things have been set in order and distinguished and placed in subjection—the heavens and the things that are in the heavens, the earth and the things in the earth, the sea and the things in the sea, fire, air, the unfathomed pit, the things in the heights and in the depths and in the realm between; God sent him to men. 3 Now, did he send him, as a human mind might assume, to rule by tyranny, fear, and terror? 4 Far from it! He sent him out of kindness and gentleness, like a king sending his son who is himself a king. He sent him as God; he sent him as man to men.
In Chapters 9 and 10, we have reference to the great Plan of God, established with His Son, Jesus Christ, that allows us to be free and capable of sinning, but also provided escape from our sins. The fruits of the Fall, including the free agency we have to choose God or to choose sin, appear to be part of God’s great Plan of Salvation, to use LDS terminology. Indeed, God’s Plan gives us power to become something much more than mere children in ignorance, but beings of knowledge and capability who can become “imitators of God” through service and charity.
Chapter 9 And so, when he had planned everything by himself in union with his Child, he still allowed us, through the former time, to be carried away by undisciplined impulses, captivated by pleasures and lusts, just as we pleased. That does not mean that he took any delight in our sins, but only that he showed patience. He did not approve at all of that season of wickedness, but on the contrary, all the time he was creating the present age of righteousness, so that we, who in the past had by our own actions been proved unworthy of life, might now be deemed worthy, thanks to God’s goodness. Then, when we had shown ourselves incapable of entering the Kingdom of God by our own efforts, we might be made capable of doing so by the power of God. 2 And so, when our unrighteousness had come to its full term, and it had become perfectly plain that its recompense of punishment and death had to be expected, then the season arrived in which God had determined to show at last his goodness and power. O the overflowing kindness and love of God toward man! God did not hate us, or drive us away, or bear us ill will. Rather, he was long-suffering and forbearing. In his mercy, he took up the burden of our sins. He himself gave up his own Son as a ransom for us—the holy one for the unjust, the innocent for the guilty, the righteous one for the unrighteous, the incorruptible for the corruptible, the immortal for the mortal. . . .
Chapter 10 If you too yearn for this faith, then first of all you must acquire full knowledge of the Father. 2 For God loved men, and made the world for their sake, and put everything on earth under them. He gave them reason and intelligence, and to them alone he entrusted the capacity for looking upward to him, since he formed them after his own image. It was to them that he sent his only-begotten Son, and to them that he promised the Kingdom in heaven which he will give to those who love him. 3 And when you have acquired this knowledge, think with what joy you will be filled! Think how you will love him, who first loved you so! 4 And when you love him, you will be an imitator of his goodness. And do not be surprised to hear that a man can become an imitator of God. He can, because God wills it.
5 To be happy does not, indeed, consist in lording it over one’s neighbors, or in longing to have some advantage over the weaker ones, or in being rich and ordering one’s inferiors about. It is not in this way that any man can imitate God, for such things are alien to his majesty. 6 But if a man takes his neighbor’s burden on himself, and is willing to help his inferior in some respect in which he himself is better off, and, by providing the needy with what he himself possesses because he has received it from God, becomes a god to those who receive it—then this man is an imitator of God.
Many interesting passages for contemplation!