The rite of Confirmation usually entails the person being anointed with oil on the forehead, sometimes called "chrism oil."
What does chrism oil, or anointing, have to do with Confirmation? And how does this help us better understand what Confirmation means?
In the fourth century, St. Augustine provided some very insightful commentary on just these kinds of questions. In his homily on Psalm 26 (in the Greek Septuagint numbering, which is Psalm 27 in modern Bibles), he comments on how the Old Testament anointing of kings and priests prefigured the priest-king role of Christ, which is now applied to all Christians.
It begins for Augustine with the heading of Psalm 26, which in Augustine's Bible read "A Psalm of David, before he was smeared (liniretur)."
Augustine took this to mean that David composed this psalm before he was smeared, or "anointed" (unctus, from where we get "unction") as king. He explains:
"In his days only kings and priests were anointed; at that time they only were anointed persons. In these two was prefigured the one future king and priest, the one Christ with both functions; and he was given the title 'Christ' in virtue of his anointing."
This was a pretty standard reading of the way in which Christ fulfilled the role of the Old Testament priests and kings. Both were consecrated to these roles with a ritual that involved an anointing with oil. Such a rite marked them off, or "sanctified" them, for their task. The word "Christos" (Χριστος) means "anointed," derived from χριω (chrio, to anoint), and is the Greek word for the Hebrew "messiah."
Augustine then applies the meaning of "anointed" to the church.
One of Augustine's key interpretive moves in the Psalms is to always try to understand how Christ and the church are related to one another. The Psalms, written by David, are nonetheless, as Scripture, the voice of Christ. But because Christ has joined himself to his body, the church, there is an intimate link between Christ and the church.
So Augustine takes the meaning of Christ as prophet and king to also apply to the church. This is a classic instance of the Augustinian interpretive principle (especially in the Psalms) of the totus Christus, "the Whole Christ, both head and body. It's all over the place in Augustine homilies on the Psalms.
"But not only was our Head anointed; his body was too, we ourselves. He is king because he reigns over us and leads us; priest because he intercedes on our behalf. What is more, he alone is priest in such a way as to be also the sacrifice. He offered to God a sacrifice that was nothing other than himself. He could not find a totally pure victim, endowed with reason, apart from himself. He is like a spotless lamb who redeemed us by his own split blood, uniting us into one body with himself and making us his members, so that in him we too are Christ."
Augustine then uses this interpretation to explain how anointing is appropriate for all Christians, not just priests or kings:
"This is why anointing is proper to all Christians, even though in earlier times under the Old Covenant it was given to two kinds of person only. From this it is obvious that we are the body of Christ, being all anointed. In him all of us belong to Christ, be we are Christ too, because in some sense the whole Christ is Head and body. This anointing will make us spiritually perfect in the life which is promised to us."
Finally, Augustine points to how this anointing relates to the sacramental rite, which intimates and prefigures the future life.
"This psalm is the cry of one who longs for that life, who longs for that grace of God which will be perfected in us at the end. That is why [the psalm] is entitled, before he was smeared. We are anointed now in the sacrament, and by the sacrament what we will be in the future is prefigured. We must long for that ineffable and indefinable future blessing, and grown while we receive it sacramentally, so that we may rejoice in the very reality of which the sacrament gives us a foretaste."*
Augustine weaves Old Testament ritual, Christology, contemporary sacramental practice, and eschatological hope into one unified, coherent practice. It's important to understand, too, that the early church didn't think about time in a strictly linear fashion--one thing after another. Rather, they understood a kind of "higher time," the time in which God's eternal plans were held, as the source of everything that happened in historical time. This is one of the reasons why Augustine can exegete this passage with reference to different historical periods so seamlessly.
But for the rite of Confirmation, and its connection with oil, there are three things to take away from this passage:
1. This rite confers on us a kingly and priestly role. Kings are given power and authority to rule and lead, and if we take Christ as our model king, then we are to rule graciously and mercifully, though not shy of judgment, that is, the ability to speak truth, even when it's hard. Priests intercede for people to God, and likewise mediate God's presence to his people. As Christians (which we could very called "anointed ones"), we are what the Scriptures refer to as a "kingdom of priests."
2. In conferring these roles, Confirmation deepens our union with Christ in the body of the church. As Confirmation confers upon us the co-kingly task, we are drawn deeper into Christ's mission of ruling and caring for creation. And as co-priests, we are drawn deeper into Christ's restoring of creation as genuinely "eucharistic" (something for which to give thanks), instead of becoming a source of idolatry or abuse. As we participate deeper in Christ's mission, we draw closer to the heart of God, who longs for the reconciliation of all things.
3. And finally, Augustine reminds us that the sacrament of Confirmation is a foretaste of heavenly perfection. It is something which we ought to long for, not only because of the immediate means of grace, as it were (becoming co-kings and co-priests), but also because of the future hope to which it directs us.
There's more to Confirmation than the ideas outlined here. But Augustine helps us understand the theological significance of using oil in the anointing ritual of Confirmation, and puts it in the broadest possible biblical context.
* This passage is from Augustine, En. Ps. 26(2).2, translated by Maria Boulding in Expositions of the Psalms: 1–32, in the Works of Saint Augustine for the 21st Century edition, volume III/15 (Hyde Park, NY: New City Press, 2000), 274–275.