In the New Testament, baptism is related closely to circumcision. Paul explains this in Colossians 2:9-12:
For in Him all the fullness of Deity dwells in bodily form, and in Him you have been made complete, and He is the head over all rule and authority; and in Him you were also circumcised with a circumcision made without hands, in the removal of the body of the flesh by the circumcision of Christ; having been buried with Him in baptism, in which you were also raised up with Him through faith in the working of God, who raised Him from the dead.
In the Old Testament circumcision was performed on the eighth day after the birth of a boy. One could be tempted from this connection to suggest that baptism should be performed on infants within the Christian community. There are, however, three notable exceptions to this pattern: 1) Abraham, 2) Ishmael, and 3) the second generation of wandering Israelites. It is the first and third exceptions that I am most interested in. Let's begin with the latter. This account is found in Joshua 5:1-9.
Now it came about when all the kings of the Amorites who were beyond the Jordan to the west, and all the kings of the Canaanites who were by the sea, heard how the LORD had dried up the waters of the Jordan before the sons of Israel until they had crossed, that their hearts melted, and there was no spirit in them any longer because of the sons of Israel. At that time the LORD said to Joshua, “Make for yourself flint knives and circumcise again the sons of Israel the second time.” So Joshua made himself flint knives and circumcised the sons of Israel at Gibeath-haaraloth. This is the reason why Joshua circumcised them: all the people who came out of Egypt who were males, all the men of war, died in the wilderness along the way after they came out of Egypt. For all the people who came out were circumcised, but all the people who were born in the wilderness along the way as they came out of Egypt had not been circumcised. For the sons of Israel walked forty years in the wilderness, until all the nation, that is, the men of war who came out of Egypt, perished because they did not listen to the voice of the LORD, to whom the LORD had sworn that He would not let them see the land which the LORD had sworn to their fathers to give us, a land flowing with milk and honey. Their children whom He raised up in their place, Joshua circumcised; for they were uncircumcised, because they had not circumcised them along the way. Now when they had finished circumcising all the nation, they remained in their places in the camp until they were healed. Then the LORD said to Joshua, “Today I have rolled away the reproach of Egypt from you.” So the name of that place is called Gilgal to this day.
There are several points that need to be mentioned form the above passage: 1) they passed over the Jordan on dry land as they did the Red Sea, 2) those born in the wilderness were not circumcised on the eighth day, and 3) after the circumcision was completed, the Lord said, “Today I have rolled away the reproach of Egypt from you.”
There are various ways to understand this last statement. David Howard, in the New American Commentary, takes the position that the reproach of Egypt was their mocking of Israel as the nation wandered aimlessly for forty years:
Egypt's “reproach” would have been occasioned by the Egyptians' observing that Israel was wandering aimlessly in the wilderness for forty years, concluding that Israel's God had abandoned it and heaping scorn on Israel because of this. This is precisely what Moses predicted Egypt would do in the event that God punished his people because of their sins (Exod 32:12; Num 14:13–16; Deut 9:28).
H.D.M. Spence, however, takes an alternative approach and considers the interpretation of scholars like Howard to be less clear and not satisfying all the requirements of the passage:
But Knobel supposes (3) that it was their down-trodden miserable condition in Egypt, a condition which was only partially ameliorated during their wanderings in the wilderness, in the course of which, accustomed to a settled existence, they must have had much to endure. “With the arrival in Canaan,” he adds, “all this came to an end. All those who had deserved punishment were dead, all the uncircumcised were circumcised, reproach and misery were put aside, and Israel, as the worthy community of God, entered on a new life.”
I tend to agree with this latter approach taken by Spence and Knobel. While their baptism into Moses in the cloud and in the sea was a step towards freedom, it wasn't until their entrance into the promised land that the promise made to them through Moses had been fulfilled. There are some interesting inferences one could make concerning this act of circumcision and the continued practice of baptism today, but that is beyond the scope of this paper because one of the presuppositions I am holding is that baptism is practiced today as stated in the introduction.
So, this circumcision exception does not exactly line up with how we practice baptism today because it has more to do with perfection than it does the original moment of justification. Therefore, we must turn our sights to the first example given above: Abraham.
As stated in the second section of this paper, Abraham was justified by faith long before he was circumcised. Here is my summary of Abraham's life from the previous articles:
It is necessary that this point to put into perspective Abraham's imputed righteousness by looking at a timeline of Abraham's life. Abraham was seventy-five years old when he left Haran (Genesis 12:4). Abraham married Hagar ten years after arriving in Canaan (Genesis 16:3). When Ishmael was born, he was eighty-six (Genesis 16:16). Abraham was ninety-nine when he was circumcised (Genesis 17:24). He was one hundred years old when Isaac was born (Genesis 21:5).
We do not see an example of someone in the New Testament waiting twenty-four or so years to be baptized. In fact, it is something done quickly in the Book of Acts. But, because of the age of the ones who submitted to baptism and Paul's usage of Abraham's circumcision to make a point about the way justification occurs in the New Testament, it seems appropriate to make the connection between the original circumcision of Abraham and baptism in the New Covenant. Notice again Paul's words:
Is this blessing then on the circumcised, or on the uncircumcised also? For we say, “FAITH WAS CREDITED TO ABRAHAM AS RIGHTEOUSNESS.” How then was it credited? While he was circumcised, or uncircumcised? Not while circumcised, but while uncircumcised; and he received the sign of circumcision, a seal of the righteousness of the faith which he had while uncircumcised, so that he might be the father of all who believe without being circumcised, that righteousness might be credited to them, and the father of circumcision to those who not only are of the circumcision, but who also follow in the steps of the faith of our father Abraham which he had while uncircumcised. (Romans 4:9–12)
Baptism, like circumcision is a sign. It is a seal of the righteousness of the faith which one has prior to their baptism. Righteousness is imputed based on one's faith. God, as Paul said in Romans 4, calls into being that which is not. When one is baptized, like when Abraham was circumcised or when he offered Isaac, then the saying “it was credited to him as righteousness” is fulfilled. Tomorrow, we will look at a specific example of this.
 Howard, David M., Jr. Joshua. Vol. 5. Nashville: Broadman & Holman Publishers, 1998. Print. The New American Commentary.
 Spence-Jones, H. D. M., ed. Joshua. London; New York: Funk & Wagnalls Company, 1909. Print. The Pulpit Commentary.