Many works have been written defending the practice of infant baptism. But few of them make use of what I would consider to be the strongest arguments in favour of the practice. Far too often the primary argument involves a direct parallel drawn between circumcised children under the old covenant and baptised children under the new covenant. Whilst not entirely lacking value as an argument, it seems like an unusual place to begin in defending infant baptism. Within this piece, I intend to give a defence of the practice on much firmer Biblical ground.
The People of the New Covenant
Who is the new covenant made with? Is it made only with adult believers who can make a mature profession of faith? Or is it made with adult believers and their children tagged on as a sort of exception to this general rule? When we turn to the scriptures, the answer is neither of these options. The real answer is given to us in the new covenant promise found in Jeremiah 31:31-34.
“Behold, the days are coming, declares the Lord, when I will make a new covenant with the house of Israel and the house of Judah.” (Jeremiah 31:31)
The new covenant is made, not with an isolated collection of individuals, but with a people, a nation. A people consisting of families (v1), of people from all sections of society from the least to the greatest (v34). It is to this people that God addresses his promise to write his law on their hearts. And we see this reflected elsewhere in the new covenant prophecies given in scripture. The prophet Joel speaks of entire households being filled with the Spirit and proclaiming the wonders of God (Joel 2:28-29). Malachi speaks of fathers and children having their hearts reconciled to one another (Malachi 4:6). In the new covenant, the whole people will have one heart united in the ways of God, both adults and children (Jeremiah 32:38-40).
And none of this is surprising considering the history of the old testament. At the time of the flood, Noah and his entire household are taken up into the ark (Genesis 6:18). When God makes his covenant with Abraham, he requires him to have all the males in his household circumcised (Genesis 17:9-10). The Passover ceremony was kept by entire households (Exodus 12:3-6) and went on to become part of a series of festivals celebrated by the entire nation of Israel (Leviticus 23). Time and again, we see God dealing with people not merely as individuals, but as households, as cities, as nations.
Corporate Language in the New Testament
It’s not just the old testament which uses this sort of corporate language to speak about God’s relationship to his people. In the Gospels, we see not merely individuals but “Jerusalem and all Judea and all the region about the Jordan” going to receive the baptism of John. We see Jesus identifying the children of Judea as fitting recipients of the kingdom of heaven (Matthew 19:13-15). And when the children of Jerusalem cry out praises to Jesus, he identifies them as the “babes and infants” from Psalm 8 whose praises God uses to silence his enemies (Matthew 21:15-16, cf. Psalm 8:1-2).
The book of Acts continues in a similar fashion. At Pentecost, the Spirit is poured out upon entire households, in fulfilment of the prophecy of Joel (Acts 2:17-18, cf. Joel 2:28-29). The promise of the new covenant represented in baptism is applied not merely to adults, but also to children (Acts 2:38-39). Even when Gentiles are incorporated into the Church later in Acts, similar language is used. Cornelius is filled with the Spirit and baptised along with his household (Acts 11:13-15), as is Lydia along with her household (Acts 16:14-15) and the Philippian Jailer along with his household (Acts 16:30-34). The use of household language throughout Acts is not unexpected given the way that God has always dealt with his people in scripture.
The same can be said of the letters of Paul. The apostle Paul addresses his letters to the “saints” of various churches (e.g. Ephesians 1:1, Colossians 1:2). And just who is included in this group of saints? Entire households, including children, servants, husbands and wives (Ephesians 5:22 – 6:9, Colossians 3:18 – 4:1). Paul would not have necessarily known about the exact status of each individual person within these households. Yet his default attitude seemed to be one of generosity, that if anyone was a member of a local Church or belonged to a Christian household, then they should be considered a true believer unless there existed some reason to believe otherwise.
One People of God
There are many differences between the old and new covenants in the Bible. However, the people of God across the two testaments remain essentially one and the same. If there were no such continuity, then the promises of the new covenant made to Israel in the prophets could never apply to the Church.
And this is the consistent teaching of the new testament. Romans 11:17-18 compares old covenant Israel to an olive tree and treats the Church as the very same olive tree, but with new branches (Gentiles) being “grafted in” to the tree and old branches (Jews who reject Christ) being “cut off” from the tree. 1 Corinthians 10:1-5 identifies the ancient Israelites who passed through the red sea as the “fathers” of the Gentile Corinthians, even going so far as to equate the red sea crossing with Christian baptism.
At the centre of all of this stands Jesus. He is the means by which faithful Gentiles can be grafted into the covenant people and enjoy the blessings of fellowship with God. He is the means by which all believers in the new covenant can enjoy the presence of God in an even greater way than old covenant Israel. Yet none of this abolishes the principle of continuity between the covenants, rather, Jesus is the means by which that continuity is established and confirmed. In him all of the promises of God are yes and Amen (2 Corinthians 1:20).
What Does it Mean?
There are, to be sure, some who treat infant baptism merely as a kind of good luck charm for the child. But this individualizes baptism, isolating it from the life of the Church. In 1 Corinthians 12:13 Paul teaches the following: “For in one Spirit we were all baptized into one body—Jews or Greeks, slaves or free—and all were made to drink of one Spirit.” In baptism, a person is incorporated into the Church, the body of Christ. As a member of the Church, they are to be brought up in the knowledge of God and formed into a mature believer.
And as Paul goes on to teach in the passage, the Church doesn’t just contain stronger believers but also weaker believers who need extra help and support (v21-25). Church is not just for those who have it all together, it’s for messy people as well. The kingdom of God is for the poorest and the richest, the least and the greatest, the youngest and the oldest. We all come together as one family under one God, marked out by one baptism.
A true and living faith in God is something to be passed from generation to generation. Living in a pluralist culture we tend to think of our faith as a private matter and so we often simply allow our children to decide for themselves what to believe as they grow up. But this is not the approach that we find in scripture. Instead, Christian parents are called to raise their children “in the discipline and instruction of the Lord” (Ephesians 6:4), just as the Israelites of old were to do with their children (Deuteronomy 6:6-7). Baptism marks the beginning of a life of discipleship and devotion to Christ.
“I am reminded of your sincere faith,
a faith that dwelt first in your grandmother Lois and your mother Eunice
and now, I am sure, dwells in you as well.” (2 Timothy 1:5)
 Given that Israelite children would also have participated in the red sea crossing, we have here an old covenant example of infant baptism.
 Within this verse, Paul echoes language from an earlier passage in the letter in which he compares details of the Exodus story with the Christian sacraments of baptism and the Lord’s supper (1 Corinthians 10:1-5).