A visionary is often described as being “ahead of his time”. In many ways, St. Maximus the Confessor embodied this descriptor when it came to his theology of the unborn. While abortion itself has always been regarded as a serious sin, Maximus argued discarded a distinction espoused by some early Church theologians of the “formed” and “unformed” fetus and rather looked to the Incarnation of Christ as his inspiration of the body and soul being united at the moment of conception.
While many people today take much of this for granted, it was not so in Maximus’ day. While abortion was always seen as immoral, the debate centered on the ancient idea of embryology that existed at the time. Many early Church Fathers had accepted the Aristotelian notion of the development of the unborn child. That is to say, they did not understand a few things that 
are understood today. It is often overlooked that early theologians simply did not have the knowledge of the human embryo that is known about today. Firstly, in ancient times there was no notion of male and female gamete cells. Microscopic human life at the basic embryonic levels was not even a consideration since there could be no observation of these things at that age. In fact, most church fathers drew a distinction between the formed and unformed fetus based upon the science of their time. While they all agreed that abortion regardless if the fetus was “formed” or “unformed”, was a grave matter since it was extinguishing God’s creative activity, they believed “ensoulment” happened when the unborn child began to move (forty days for a male and ninety days for a female). This ensoulment, for the early fathers, meant that the child had been” formed” since it now has a rational soul and moves. Otherwise, what existed prior to the time of the “formed” child”, according to many Church Fathers, was blood becoming flesh.
What makes Maximus so interesting is that in his argument for the Incarnation he rejects his peers’ distinction of the unborn child. In his Ambiguum he states the following, “The soul arises at conception simultaneously with the body to form one complete human being. The body, of course, is created from the underlying matter of another body at conception, and at once enters into synthesis with the soul to form one species with it” (See Ambiguum 42). He posits this to make an important point that is that Christ is like humanity in all things except sin. That is why he continues,
And in the same way, the Creator of humanity was he who assumed his body from the immaculate Virgin, as if from undefiled earth, and who, endowing it with life for himself (what again, the Logos knew as soul and the image of God), fashioned his own humanity. Or rather, the Creator of humanity was he who, as almighty and immutable, willingly for our sake fashioned his own manhood at the time he took the flesh and animated it with an intelligent and rational soul (Ambiguum 42).
One needs to ponder Maximus’ proposition for a moment. Consider the passage in Luke where Mary visits her relative Elizabeth. By this time Mary is just a few days pregnant. In this passage the unborn John leaps within his mother’s womb when Mary arrives and greets his mother. Furthermore, Elizabeth refers to the child within Mary’s womb as “my Lord” (see Luke 1: 38-43). If the child is “unformed” then the leaping of John and Elizabeth’s proclamation do not make any sense. How is this “unformed” creature divine? Why would it be called “Lord”? This is a decidedly important criticism of his peers who have not discovered this important point within Scripture. It only stands to reason that Christ is fully human and fully divine when this happens. Maximus is acknowledging the Divine personhood of Christ, but also human personhood as well.
This, of course, goes to the very definition of the word “person”. But what is meant by this term? One can naturally look at the Christian philosopher Boethius since he gives such a thorough definition of the word, “A person is an individual substance of a rational nature” (Liber de Persona et Duabus Naturis, Ch. 3). This particular vision of personhood is important because it denotes that any substance of a rational nature is a person so one can include God, angels, demons, and humans. All of these “substances of rational natures” have the ability or the potential to be rational or rather intellectual. Maximus is clear in his presentation that Jesus, when He takes flesh, fuses His human nature “with an intelligent and rational soul.”
Again, for Maximus, Jesus is like humanity in all things except sin. So if Christ infuses his human nature with a rational soul at conception then it stands to reason that the human being, at conception, is infused with a rational soul. This is not some conjecture, rather it is a reasonable position given the Christology and the scientific knowledge that exists. As Pope Benedict XVI has stated, “It is not an accumulation of biological material but rather of a new living being, dynamic and marvelously ordered, a new individual of the human species. This is what Jesus was in Mary’s womb; this is what we all were in our mother’s womb. We may say with Tertullian, an ancient Christian writer: “the one who will be a man is one already” (Apologeticum IX, 8), there is no reason not to consider him a person (emphasis added) from conception” (see “Celebration of First Vespers of the First Sunday of Advent for Unborn Life” by Pope Benedict XVI, November 27, 2010). While Pope Benedict XVI does not mention Maximus, one can see his theology in Benedict’s comments: 1) That the conceptus is a being (formed), 2) it has a rational nature (intellectual soul), and 3) that when Jesus took on human nature he went through the same process of development within the womb like all human beings.
While St. Maximus was not the only early Church theologian to disregard the formed/unformed distinction, for example, St. Basil disregarded this distinction (see Canons 2 and 8). However, Maximus was the Church Father who further elaborated the idea that there was no distinction in the embryo by using the Incarnation to make his case. Simply, it would make no sense for Elizabeth to proclaim to Mary that she is the mother of “my Lord” if the child within Mary’s womb it is something else less than fully the Lord in both his humanity and divinity present. In many ways this expresses the thought of the Church when it declares, “The human person, created in the image of God, is a being at once (emphasis added) corporeal and spiritual” (see Catechism of the Catholic Church, no. 362). Furthermore, it goes on to state, “The Church teaches that every spiritual soul is created immediately (emphasis added) by God – it is not “produced” by the parents – and also that it is immortal” (Ibid, no. 366). Maximus’ thought has trickled down through the centuries. Christ, in his conception, was both fully human and fully Divine. Even in His conception He was truly like humankind in all things except sin.