This post is based on the book, “The Anglican Evangelical Doctrine of Infant Baptism”, which is a set of two essays on baptism, the first by John Stott and the second by J. Alec Motyer. In this post I try to consolidate the two essays and bring out the key points to help me clarify their message.
The essays say that baptism should be understood in light of three Old Testament covenants, to Noah, Abraham and Moses; and particularly the Abrahamic covenant. So, first let’s look at the New Testament references to baptism, and relate them back to these covenants.
Peter links baptism to Noah in 1 Peter 3:21.Paul, in 1 Corinthians, describes the exodus, and the passing through the red sea, as a baptism into Moses, and as drinking from the spiritual Rock of Christ:
1 Corinthians 10
 For I do not want you to be unaware, brothers, that our fathers were all under the cloud, and all passed through the sea,  and all were baptized into Moses in the cloud and in the sea,  and all ate the same spiritual food,  and all drank the same spiritual drink. For they drank from the spiritual Rock that followed them, and the Rock was Christ.
Paul in Colossians 2 also links baptism to the Abrahamic covenant:
 In him also you were circumcised with a circumcision made without hands, by putting off the body of the flesh, by the circumcision of Christ,  having been buried with him in baptism, in which you were also raised with him through faith in the powerful working of God, who raised him from the dead.  And you, who were dead in your trespasses and the uncircumcision of your flesh, God made alive together with him, having forgiven us all our trespasses,  by canceling the record of debt that stood against us with its legal demands. This he set aside, nailing it to the cross.  He disarmed the rulers and authorities and put them to open shame, by triumphing over them in him.
Here Paul talks about the circumcision of Christ, and describing it as a spiritual circumcision and contrasting to physical circumcision. In v12, this circumcision of Christ is through baptism, though which we are buried and raised with Christ.
So if baptism is the new circumcision, it’s worth looking back at what God said to Abraham when he gave the covenant and sign of circumcision, in Genesis 17:
 When Abram was ninety-nine years old the LORD appeared to Abram and said to him, “I am God Almighty; walk before me, and be blameless,  that I may make my covenant between me and you, and may multiply you greatly.”  Then Abram fell on his face. And God said to him,  “Behold, my covenant is with you, and you shall be the father of a multitude of nations.  No longer shall your name be called Abram, but your name shall be Abraham, for I have made you the father of a multitude of nations.  I will make you exceedingly fruitful, and I will make you into nations, and kings shall come from you.  And I will establish my covenant between me and you and your offspring after you throughout their generations for an everlasting covenant, to be God to you and to your offspring after you.  And I will give to you and to your offspring after you the land of your sojournings, all the land of Canaan, for an everlasting possession, and I will be their God.”  And God said to Abraham, “As for you, you shall keep my covenant, you and your offspring after you throughout their generations.  This is my covenant, which you shall keep, between me and you and your offspring after you: Every male among you shall be circumcised.  You shall be circumcised in the flesh of your foreskins, and it shall be a sign of the covenant between me and you.  He who is eight days old among you shall be circumcised. Every male throughout your generations, whether born in your house or bought with your money from any foreigner who is not of your offspring,  both he who is born in your house and he who is bought with your money, shall surely be circumcised. So shall my covenant be in your flesh an everlasting covenant.  Any uncircumcised male who is not circumcised in the flesh of his foreskin shall be cut off from his people; he has broken my covenant.
God makes the covenant with Abraham, promising to be his God, that Abraham will be father of many nations, and will have an everlasting land. Circumcision is the sign of this covenant. We know that this covenant to Abraham is fulfilled through Christ, and it makes sense that even though the physical circumcision has been done away with after Christ has come, we should still have a sign of this same covenant, which is baptism, as Paul described above in Colossians.
It’s also interesting to note that the circumcision was to be done to the boys of 8 days old, or for foreign adults when they are brought into Israel. We could equate this to infant baptism for those in church and adult baptism for those who weren’t born to a Christian family.
Paul in Galatians 3 discusses this continuation of Abraham’s promise in Christ, and mentions the baptism that is included in putting on Christ:
 Now before faith came, we were held captive under the law, imprisoned until the coming faith would be revealed.  So then, the law was our guardian until Christ came, in order that we might be justified by faith.  But now that faith has come, we are no longer under a guardian,  for in Christ Jesus you are all sons of God, through faith.  For as many of you as were baptized into Christ have put on Christ.  There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus.  And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.
2. Meaning of baptism
Baptism is a sacrament of grace. This is shown by being baptised by someone else, rather than doing it to yourself. Similarly, the Old Testament covenants that God made with His people were of His grace.
Baptism signifies a number of things. First, union with Christ: the baptism is into Christ, as we have seen above, and can also read in Romans 6v3 “Do you not know that all of us who have been baptised into Christ Jesus were baptised into his death?”. And so baptism also signifies participation in His death and resurrection.
Baptism also signifies forgiveness of sins, for example Acts 22v16: “Rise and be baptised and wash away your sins, calling on His name”. And it signifies the gift of the Holy Spirit, for examples Matthew 3v11 “I baptize you with water for repentance, but he who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire”, or we could also look at Acts 2 v38-39 (quoted in section 4 below).
3. Effect of baptism
While baptism signifies many things, it does not make them true. We can look at Simon in Acts 8 for an example of this:
 But there was a man named Simon, who had previously practiced magic in the city and amazed the people of Samaria, saying that he himself was somebody great.  They all paid attention to him, from the least to the greatest, saying, “This man is the power of God that is called Great.”  And they paid attention to him because for a long time he had amazed them with his magic.  But when they believed Philip as he preached good news about the kingdom of God and the name of Jesus Christ, they were baptized, both men and women.  Even Simon himself believed, and after being baptized he continued with Philip. And seeing signs and great miracles performed, he was amazed.  Now when the apostles at Jerusalem heard that Samaria had received the word of God, they sent to them Peter and John,  who came down and prayed for them that they might receive the Holy Spirit,  for he had not yet fallen on any of them, but they had only been baptized in the name of the Lord Jesus.  Then they laid their hands on them and they received the Holy Spirit.  Now when Simon saw that the Spirit was given through the laying on of the apostles’ hands, he offered them money,  saying, “Give me this power also, so that anyone on whom I lay my hands may receive the Holy Spirit.”  But Peter said to him, “May your silver perish with you, because you thought you could obtain the gift of God with money!  You have neither part nor lot in this matter, for your heart is not right before God.  Repent, therefore, of this wickedness of yours, and pray to the Lord that, if possible, the intent of your heart may be forgiven you.  For I see that you are in the gall of bitterness and in the bond of iniquity.”  And Simon answered, “Pray for me to the Lord, that nothing of what you have said may come upon me.”
In v13 we see Simon is baptised, but his later actions show he is not faithful, and Peter condemns him in strong langauge in v20-22. So clearly being baptised had not saved him. Similarly we should not think baptism gives someone faith, or means that they have faith. It is only a seal on their faith, if they have that faith.
Paul in Romans 4 explains that circumcision was a seal of what Abraham had already received by faith :
 “Blessed are those whose lawless deeds are forgiven, and whose sins are covered;  blessed is the man against whom the Lord will not count his sin.”  Is this blessing then only for the circumcised, or also for the uncircumcised? For we say that faith was counted to Abraham as righteousness.  How then was it counted to him? Was it before or after he had been circumcised? It was not after, but before he was circumcised.  He received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. The purpose was to make him the father of all who believe without being circumcised, so that righteousness would be counted to them as well,  and to make him the father of the circumcised who are not merely circumcised but who also walk in the footsteps of the faith that our father Abraham had before he was circumcised.
Similarly, baptism is a seal on the blessings of the covenant. In the case where someone is baptised before they have faith, they can then claim the inheritance of faith when they do come to believe.
4. Comments on infant baptism
Baptism is clearly the right thing to do for an unbaptised believer, for example it is included in Jesus’ commission to his discipes in Matthew 28v19: “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you”
Going onto infant baptism we can consider a number of things, and bearing in mind we have already noted the inclusion in the Abraham covenant of the circumcision of babies.
In Mark 10, we see Jesus’ response to children being brought to him:
 And they were bringing children to him that he might touch them, and the disciples rebuked them.  But when Jesus saw it, he was indignant and said to them, “Let the children come to me; do not hinder them, for to such belongs the kingdom of God.  Truly, I say to you, whoever does not receive the kingdom of God like a child shall not enter it.”  And he took them in his arms and blessed them, laying his hands on them.
While not mentioning baptism, the essays argue that seeing what Jesus says about the children, and wanting them to come to Him, that this would support wanting children to be baptised and have the sign of his covenant.
In Acts 2 v38-39 we see Peter call the listeners to be baptised, and he also says that this promise is for them and their children:
 And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.  For the promise is for you and for your children and for all who are far off, everyone whom the Lord our God calls to himself.” (Acts 2:38-39 ESV)
Paul in 1 Corinthians 7v14 says “For the unbelieving husband is made holy because of his wife, and the unbelieving wife is made holy because of her husband. Otherwise your children would be unclean, but as it is, they are holy”. So the children of believers are not unclean or unholy, and so they should share in the covenant sign for this.
In conclusion, Motyer’s essay notes that we should baptise, having faith and praying that God will perform His work in them. This applies to both infant and adult baptism. In both cases, we should trust in God.