Iranaeus On the Unity of Creation and Redemption
The early Gnostic view of the world is comprised of a complex myths in which the eons, or spiritual powers, are constantly “playing catch up.” The God of the Old Testament is an accident, made through the error of one eon, who then himself creates the material world. The eons are than forced to try to slip the spiritual world into the material world, until they send Jesus in the appearance of a man to rescue those he has chosen from the material world by leading them into a spiritual knowledge. In contrast, Iranaeus sees all of history as working out the divine plan, rather than a series of “playing catch up” to make up for the accident of creation.
In Iranaeus’s thought, the goal of redemption is perfection. The goal of perfection is not a response to sin, but is the original intent of creation. Humanity was not originally created perfect:
But created things must be inferior to him who created them, from the very fact of their later origin-for it was not possible for things recently created to have been uncreated. But since they are not uncreated, they come short of being perfect: as those who come into being, they are like infants, unaccustomed to and unexercised discipline…it was possible for God to have made humankind perfect from the first, but humanity could not receive this, since they were still like infants. This is why our Lord in these last times, having summed up all things in himself, came to us, not as he might have come but as we were capable of beholding him. 
As created beings, humanity could not receive perfection at first, but must be made perfect through Christ, who became a human to unite all humanity with God.
Sin did not change God’s divine plan. “Adam’s sin was ‘child-like’, a seemingly inevitable stage in the growth of humanity to maturity.”  Sin was merely an infant and imperfect humanity exercising its free will. In the work of perfecting humanity, Christ would have to deal with sin, restore the image of God, and bring creation to full maturity, which eliminates the immaturity that led humanity to sin.
This is the order, this is the rhythm, this is the movement by which man, that created and organized being, is established in the image and likeness of the uncreated God. The Father, in His good pleasure, commands, the Son works and fashions, the Spirit nourishes and gives increase, and slowly but surely man makes progress and attains perfection, that is to say, comes close to the Uncreated. 
In the context of Iranaeus’s thought, sin was not an accident that God was forced to respond to, but was part of the natural process of creation and redemption that God had planned at the beginning.
It was necessary that humankind should in the first instance be created; and having been created, should grow; and having grown, should be strengthened; and being strengthened, should abound; and abounding, should recover from the disease of sin; and having recovered, should be glorified; and being glorified, should see his Lord. For God is the one who is yet to be seen, and beholding God leads to immortality, but immortality brings one near to God. 
For the Gnostics, salvation meant being saved from creation, but for Iranaeus, salvation meant bringing creation to its logical conclusion: full maturity and perfection through union with God. This union was accomplished by God’s own union with humanity through the person of Jesus Christ, who is God taken on human flesh.
When the Word of God became flesh, he confirmed both of these: he showed forth the image truly, since he himself became what was his image, and he reestablished the image after a sure manner, by assimilating humanity to the invisible father by the visible Word. 
Creation was made by God and declared to be “good”. In Christ, through His work of redemption, creation is concluded and made “perfect” in Him.
 Iranaeus, Against Heresies, 4.38.1
 David Rylaarsdam, “The Unity of God (as Creator and Redeemer) and the Unity of Human History according to Iranaeus, p. 1
 Iranaeus, Against Heresies, 4.38.3
 Ibid. 5.16.2