Christenings didn’t happen in the church where I grew up. That’s because, for my first decade, despite going a school with a Church of England ethos, on Sundays I went to an Open Brethren church.

It was the sort that wouldn’t actually call itself Brethren but would simply say it was “evangelical”. It had a baptistry under the wooden floor where adult or teenage believers could be baptised by immersion.

In Sunday school, we were taught about believers’ baptism, which seemed the biblical way of doing things.

Later, we switched to an Anglican church and, at the age of 14, I decided to get baptised.

The vicar was happy to this by full immersion. The only catch was that the church didn’t have a pool – although the vicar said he’d ideally like to have one installed.

So I took confirmation classes in preparation. And then, when the local Baptist church organised a baptism service, the vicar and I piggy-backed on it, and a week later I was confirmed by a bishop.

Infant baptism always seemed to me to be harmless, given that baptism was symbolic, but I didn’t get why the church followed it.

However, two sources helped me develop an appreciation for infant baptism: firstly, the notes explaining the theology of infant baptism in Common Worship and, secondly, Scot McKnight’s book It Takes a Church to Baptize.

So what’s really behind infant baptism?

God’s grace comes first

First of all, infant baptism is a representation of God’s prevenient grace. Prevenient is jargon meaning “grace that precedes”. It is the grace that helps people to believe before conversion.

Prevenient grace is an important concept in Christianity. Common Worship says it is “central” to baptism, which it calls “acted evangelism”.

Instead of thinking that salvation is something that we earn through what we do, it’s actually something we don’t deserve but which God has initiated through his grace.

That may be a rather difficult concept in modern society where it’s very easy to think in terms of rights and entitlements. But as Christians we believe both that it is in our nature to sin as a result of The Fall, but also that all of us do indeed sin. That creates a separation from God which, out of love, he rectified on the cross.

So, in an infant baptism, we are celebrating the prevenient grace that helps draw people to God. The acceptance of God’s grace is then symbolised in Confirmation.

Infant baptism as circumcision

Secondly, Paul in Colossians 2 makes the connection between baptism and circumcision. He tells the Christians he is writing to that they have been circumcised but not in the traditional Jewish way.

Instead, they have been “circumcised by Christ, having been buried with him in baptism”.

Thus, just as circumcision in the Old Testament is “the sign of the covenant” made in Genesis 17, infant baptism is the sign of joining the new covenant family of God.

As such, infant baptism helps children have a feeling of belonging in the church. John Calvin spoke of how infant baptism cheers up the parents with “spiritual joy” and gives a “strong stimulus” for mum and dad to bring the children up as Christians.

He wrote: “For when we consider that immediately from birth God takes and acknowledges them as his children, we feel a strong stimulus to instruct them in an earnest fear of God and observance of the law. Accordingly, unless we wish spitefully to obscure God’s goodness, let us offer our infants to him for he gives them a place among those of his family and household, that is, the members of the church.”

Those who are Christened are being “grafted into the church”, as the Articles of Religion put it.

Common Worship explains: “Baptism is the outward sign and ritual mark of incorporation into the people of the New Covenant, sealed by Christ’s death. God gives the covenant (Exodus 19.3–6; Jeremiah 31.31–34; 1 Corinthians 11.25; 2 Corinthians 3.6); it carries unfolding obligations, but these are the response to God’s grace, made possible by his Spirit.”

This inclusivity echoes Jesus’s radical view of the importance of children and the respect and care they deserve.

The Common Worship liturgy starts the presentation of the candidates for baptism with: “Jesus said, ‘Let the children come to me. Do not stop them’… Christ loves them and welcomes them into his Church.”

The early church baptised infants

Thirdly, infant baptism does seem to be practised in the New Testament and was widely performed by the early church.

In Acts 16 and in 1 Corinthians 1, we have people being baptised “with her household”, “with all his family” and with “also the household”.

In modern times, if trying to make the passages fit our theology, we might try to define household as without the children, but that does not appear to be how first century readers would view it.

After all, if infant baptism really were a newfangled idea introduced after the New Testament period, we would expect to see evidence of debates about its introduction in the second and third centuries. But there’s no evidence that such debates ever occurred.

It was only in early modern times with the Anabaptists in the Radical Reformation of the 16th century that we have evidence of anyone disputing the baptism of children.

That’s why the key continental voices in the mainstream Reformation – Martin Luther, John Calvin and Ulrich Zwingli – were all in favour of infant baptism.

Just think about that for a moment. When Luther was writing his Ninety-five Theses, containing all the things he thought the Catholic Church had got wrong, infant baptism was not among them.