Daniélou, Jean, S.J. "Chapter Two: The Baptismal Rite." The Bible and the Liturgy." Notre Dame, IN: University of Notre Dame Press, 1956, pp. 35-53.
Daniélou observe that the catechetical preparation, though very important, is done for those who are still outside the Church. It is not until the baptism itself that the person actually enters the church body (Daniélou 1956, 35). Cyril of Jerusalem described it as an entrance from the vestibule into the king's palace (Procatechesis XXXIII, 333A). Daniélou notes that we have at least one third century baptistry which features artistic depictions of the Fall on one side and Christ welcoming his people on the other side (Daniélou 1956, 36). The shape was often an octagon, with the number eight serving as a symbol of the resurrection (Daniélou 1956, 37).
The candidate, led into the baptistry, is stripped of his clothing, symbolic of taking off the old man (Daniélou 1956, 37). It may also serve as a symbolic identification with Christ, who was stripped before being crucified. Both symbols are used by Cyril (Daniélou 1956, 38). Gregory of Nyssa compares the stripping to the covering given to Adam, garments of skin, which required death. Again, it is a return to the nakedness of creation (Daniélou 1956, 39). Theodore of Mopsuestia further compares it to a removal of the fig leaves which Adam and Eve used to cover themselves.
Following the removal of the clothes, there is anointing with oil, symbolic of the richness of God and the power of Christ's purity (Daniélou 1956, 40). It is also considered a sign of God's healing and strengthening power. The metaphor of struggle and battle is carried out through the Easter vigil, as it has been in progress throughout Lent (Daniélou 1956, 41).
In some places, the water used for the baptism itself would be blessed, indicating that water by itself would not cleanse from sin (Daniélou 1956, 42). The old man would enter the water and the new man would emerge. Again, Cyril finds a parallel to Christ, this time in his death and resurrection (Daniélou 1956, 43). The theme of death, burial, and resurrection is very common in early Christian understanding of baptism. Daniélou discusses and illustrates this at some length.
An additional piece of symbolism in baptism is that of birth. Daniélou notes that this theme, of the Church as mother giving birth to children, was most likely developed in African thought (Daniélou 1956, 47-48).
After the baptism, the believer is clothed with a pure white garment (Daniélou 1956, 49). This symbolizes the new, the pure, and God's grace. Again we see echoes of Adam's purity having been stripped away and then his being clothed by God's hand. The clothing is seen as a robe of glory, provided by God (Daniélou 1956, 51).