Baptism’s biblical themes remain salient in the theology and practice of the early Church. When we baptize an infant today, for instance, we don’t immediately identify it with the death of Jesus. But in the early Church, they did. That’s why it’s worth our time exploring baptism as it was described and lived out in early Christianity. It helps us see better baptism’s biblical essence.

Baptism in the early Church was a richer experience — biblically, culturally, psychologically, sensually — than it commonly is today. Fonts, for instance, (that is when Christians began using things like fonts) were often cut into the ground, tomblike in shape, sometimes with black floors. Some fonts have even been shaped like coffins. Also, in the early Church people were often baptized in the nude, as St. Cyril of Jerusalem put it, imitating Christ who hung naked on the cross (“Mystagogical Catechesis,” No. II.1). Perhaps the young man leaving his clothes at the foot of the cross in Mark 14:52 alludes to this practice. In some places, the newly baptized were given a bit of honey and milk to taste after baptism, a symbol of entering the Promised Land.

The Didache, basically a first- or second-century manual on Christian worship and practice, describes the ritual of baptism. “[I]mmerse in running water ‘In the Name of the Father, and of the Son, and of the Holy Spirit’. If no running water is available, immerse in ordinary water. This should be cold if possible; otherwise warm. If neither is practicable, then pour water three times on the head ‘In the Name of the Father, and of the Son, and of the Holy Spirit’” (Didache, No. 7). Baptism, according to this text, was to be performed in “living water,” that is, in a stream or river. Requirements such as these were less emphasized over time, obviously, as Christianity spread into areas where “living water” was perhaps less available or desirable. However, that baptism should be performed in the name of the Trinity, either by sprinkling or immersion, remained essential — as it does to this day.

In Matthew and in the Didache, we still see the command to baptize in the name of the Trinity. Also as in the Didache, we see the communal aspect of baptismal preparation. In the Didache, both the “baptizer and the baptized” are to fast before baptism (Didache, No. 7). In an account from St. Justin Martyr, writing from second-century Rome, those already baptized are to pray and fast “with them,” that is, with those preparing for baptism. Here also we see the traditional description of baptism as “illumination,” the spiritual liberation of the intellect to see things as they are. In Pseudo-Dionysius’s description of baptismal illumination, he wrote that first, the candidate for baptism had to admit “his lack of the truth beautiful” (“The Ecclesiastical Hierarchy,” No. 396). Baptism was thought, you see, to be an initiation into light and truth, for Christ is light and truth (cf. Jn 8:12; 14:6).

But what’s the effect of baptism? Following the African theologian, Tertullian, like St. Justin Martyr, the effects of baptism were described in terms of cleansing, consecration, illumination and strengthening. He writes that in baptism the flesh is “cleansed,” “anointed,” “consecrated” and “signed.” These are all biblical images. The soul also is “fortified” and “illuminated.” The flesh is fed the body and blood of Christ, and the soul is “fattened on its God.” That is, as the Catechism of the Catholic Church states, baptism is a gateway and a door: it opens up for the baptized person new life in Christ and also life in the rest of the sacraments. Again, baptism is a kind of birth, after which that new life must be given the food necessary to grow — hence, the other sacraments.

We also learn a lot from St. Cyril of Jerusalem who clearly echoes Paul’s teaching, especially how the newly baptized are in Christ, taking on Christ, and sharing in his destiny. “Having been baptized into Christ and having put on Christ you have been conformed to the Son of God, for God predestined us to be adopted sons and made us to share in the likeness of Christ’s glorious body” (“Mystagogical Catechesis,” No. III.1). This is important because it makes clear that baptism was not considered some mere symbolic ritual, but something more significant, more indelible. This was regeneration — a rebirth into a truly new life.

It’s a new life, in fact, in God himself. St. Augustine teaches this when he talks about baptism as the gift of the Holy Spirit, the gift which makes us one with the Father and the Son in the Spirit. The Father and the Son “wished us to have communion both with them and among themselves,” he wrote. So “the Holy Spirit who is God and the gift of God” is given in baptism, and by that gift, believers are “reconciled to the Godhead” and “enjoy the Godhead” (Sermon, No. 71.18). That is, in baptism believers are given the gift of sharing in God’s own life, sharing in his divine nature (cf. 2 Pt 1:4). It’s beautiful also how Augustine sees baptism as the way God accomplishes his desire to draw us into communion with him — the Father and the Son wished us to have communion with them. One can’t help but recall Jesus’s desire for his disciples in John 17:24 — which we explored at the beginning of What We Believe. Baptism, in a sense, is the sacrament of God’s desire for us. I’ve said before, we can view the sacraments as sensual expressions of God’s love and desire for us. Isn’t that so beautiful?

These then are some of the themes salient in Catholic tradition regarding baptism. They’re the same as those found in the Bible. Baptism is no mere ritual. Rather, it’s truly a rebirth in Christ. In baptism, we’re forgiven. We’re also given hope in all our moral struggles. Our mind is opened. We’re sealed and set apart. We’re claimed by Christ, taken into his very life. As St. Thomas Aquinas said of it, Baptism “opens the gates of the heavenly kingdom” (“Summa Theologiae,” No. 3.69.7) Again, no mere ritual, we’re talking about something more real. The Church is no mere organization; it’s the body of Christ. The baptized Christian is no mere human being, but mystically and truly another Christ. We’re talking about something spiritually organic, to put it strangely. We’re not talking about some divine juridical act or some sinner’s acquittal, but about birth and growth in Christ as real children of God. We’re talking about a necessary rebirth, for how does one have life any other way? Which is why we Catholics have always insisted upon it. Because this is what baptism means.

Father Joshua J. Whitfield is pastor of St. Rita Catholic Community in Dallas and author of “The Crisis of Bad Preaching” (Ave Maria Press, $17.95) and other books. Read more from the series here.