Just as God had created Adam free and had allowed him to undergo the serpent’s temptation, so too does He leave the newly baptized person free and permits the demons to tempt him. God allows this in order that man might not be saved despite himself, but rather that he might manifest the whole reality of his will to be healed in Christ–as well as the degree of his attachment to God–in his resistance to the temptations. He further allows this in order that man might become the free co-worker in his own healing, salvation, and deification, and in order that he might personally and voluntarily make his own the gifts he has received.
If man were to strive with all his being to preserve and assimilate to himself the grace conferred in the sacraments without ever departing from this path, he would remain in the state of health and purity that baptism had restored to his nature. The Fathers point out that it is not a priori impossible for man to lead a life in which he would commit no sin and would keep all Christ’s commandments, but that in fact, very few baptized persons have really been aware of all the grace they have received.
In regard to baptism, St Symeon the New Theologian writes: “All of us are far from having recognized the grace, the illumination, indeed the simple fact of such a birth! No, scarcely one in a thousand, or even one in ten thousand, have recognized this in mystical contemplation, whereas the others–all of them–are stillborn infants who are unaware of Him Who brought them into the world.”
~Dr Jean-Claude Larchet (Therapy of Spiritual Illnesses vol.2 pp.70-71)