Here baptism is an initiation into the family of the organized institution of the church.   Evidently it was an initiation ceremony. Every religion had and still have their own initiatory rites, which is considered sacred, mystical and given to the elect only.  Baptism was one like that.  Such open confession was necessary during the period of persecution and Christian hunting to safeguard the members.  This was the only way one could make sure of the truthfulness of the brethren. 
 What are some of the initiation ceremonies used by other religions? 
 Graduation ceremony, puberty rites, marriage ceremony, burial ceremony and subsequent rites, club and secret society initiations, raging in college’s etc are examples we are all familiar with. 
 Baptism is a naming ceremony, where an individual is given a new name and accepted within the community as an identity.  In Baptism of the new converts, even today a new name is given.  Bishops and kings are given a new name during their ordination. 

In any society there are two types of ceremonies 

1.  The rites of initiation or  rites of transition or rites of passages 
This is a once in a lifetime act whereby the society accepts the persons new status in society.  It is a seal.  The seal has meaning only if the document contains the matter after the fact.  Otherwise, the seal is really void or is an affirmation of what is contained. 
e.g.  Puberty, marriage, funeral, anunayanam, entering sanyasa, raaging, secret society initiations, rotary installation 

2. The rites of intensification 
   e.g. Prayer fellowship, worshiping together in church, saluting the flag every morning, picnics, club meetings.  It is in coming together that motivation is established and the faith reaffirmed.  Those who miss the church regularly are often weak Christians. 
    

Evidently baptism is a rite of initiation.  This aspect is very important to remember. Baptism is not the end, but a beginning. If baptism was the end of the Christian growth or faith or sanctification then we will have to wait until it is accomplished. Then baptism becomes graduation ceremony. Unfortunately in Christian Growth we get our graduation only in heaven.

Some understanding in this can be obtained by looking at the Great Commission.:

Matthew 28:19-20

Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age. Amen

Mark 16:15-16

"⁵ And he said to them, "Go into all the world and preach the gospel to the whole creation. ¹⁶ He who believes and is baptized will be saved; but he who does not believe will be condemned. ¹⁷

As I have mentioned earlier these two verses refers to the same event and same command as reported by two evangelists. One should image that both heard these commission together. The difference should be therefore only in the way they understood the order.

Mathew understood it as: Disciple all nations how? Baptizing, …. Teaching

Mark understood it as: Preach to whole creation. Baptize those who believe.

Baptism is equivalent to teaching and discipling. What Jesus is ordering is to go to all nations and tell about Jesus. Those who believe you, you make them disciples i.e. to teach them to observe all things. How could people believe the preacher? Mark 16:20 And they went forth and preached everywhere, while the Lord worked with them and confirmed the message by the signs that attended it. Evidently the Lord referred here is the Holy Spirit. (Early Church considered Jesus and Holy Spirit as a unity)

Replace baptized by "become a disciple of Jesus" or "taught about Jesus" we get the actual meaning of the verse. If we look at all the conversions in the New Testament we see that all of them were baptized immediately on hearing the word of God, immediately, within the hour, right there.

This idea is inherent in the Jewish concept of ablutions \endash mikvah. Hebrew word for the mikvah the pool of immersion is the same word used for hope as in Jer. 14:8. It has the root \ldblquote vue\rdblquote , which means "to wait for," or, "to have hope.". So jewish baptism indeed was an immersion in the hope of salvation. However the usual meaning of mikvah is "gathering" or "collecting." Mikvah is a collection or gathering of water for ritual washing. The meaning of mikvah is simply "gathered together" . Waters also symbolizes nations. The essential meaning of Christian baptism is to gather together in Christ from all nations. This is the emphasis of the wording "baptized into Christ"and "Baptized in the name of " In this sense baptism is the gathering together of people from all nations into the body of Christ.

A Study of Conversion in the Book of Acts

In every case baptism took place within a day or in a few hours of preaching the gospels. It certainly could not have been a doctrinal treatment . They simply came to the knowledge of Jesus. They were immediately baptized. Then we see that the Preachers stayed with them and instructed them extensively and it continued without end. The Apostles made several journeys in and out and wrote letters and sent messengers to instruct further. So we see that Baptism was simply a process by which the baptizer took these people as their disciples. Most cases we are told that they were given extensive instructions oIn the case of Paul, he went into the deserts of Arabia and was caught up into Paradise—whether in the body or out of the body I do not know, God knows— and he heard things that cannot be told, which man may not utter. (2 Cor 12:4). The point is that baptism was an initiation into Christian life followed by extensive instruction into Christian living and never the other way round.

The commission of our Lord Jesus in Matthew 28: 19-20 commands us to make disciples by "baptizing and teaching." If we read this text chronologically, we would contend that teaching follows Baptism. But, it is not intended to be chronological. It is simply explaining how to make disciples. You make disciples by baptizing and teaching. The order is immaterial. Baptism does not bring salvation it is only an initiation into discipleship – a initiation into learning. It is a beginning and not an end. Actually that is how Gurus everywhere in the world made disciples. That is how John the Baptist and Jesus made disciples. (Jn 4:1 "Jesus is making and baptizing more disciples than John") In the Brahminic tradition the disciples were brought to the Guru by their family and presented their gifts (Dhakshina). Then they were initiated with the sacred thread (punu nool) and then they were given the first lessons. This sacred thread ceremony is the second birth of the Brahmin whereupon he is given the Brahma Jnana (Knowledge of Salvation) and he becomes Twice Born (Dwijan).

We see here the real confusion of what exactly is baptism. Is it an initiation into discipleship or a graduation after discipleship into full salvation? Is it an acknowledge of their achievement? At what point do we give baptism then? We will have to delay the baptism till death bed? People sometime say we should wait till the age of responsibility. What age is that? When is a man mature enough to make a decision? Any missionary will know that a person is to be baptized as soon as he acknowledges the Lordship of Jesus and is willing to learn further. In a way his salvation depends on this first step. Thus baptism leads to salvation, though salvation is not attained through the ritual of baptism.

As soon as the person (individually) or family (by the decision of the head of the family) or tribe (by the decision of the chief of the family) accept Jesus they are baptized collectively (baptizing the nation) and the church jointly teaches them into all truth. Those who believe and confess and do all things that Jesus commanded them to do will be saved.

This is the only possible explanation that is possible without conflict with other passages in the bible concerning salvation. Unless the ritual of baptism is understood as an initiation into the study of Jesus we are bound to produce heresies and hair splitting arguments such as
Baptism Regenerates, Baptism Saves, Without Water Baptism there is no salvation;
Baptism must be in the name Jesus, Baptism must be in the name of Father, Son and the Holy Spirit;
Baptism should be immersion, sprinkling or pouring;
Baptism should be one immersion, it should be three immerions;
One should stand up or sitdown or lie down while being baptised;
Immersion should be backward; it should be forward;
It should be after 18 years of age, It should be as infant etc.
When baptism is a sacrament and ritual sufficient or at least necessary for salvation in the absolute literal sense everything will become complicated.

2. Baptism was a counter

Baptism was used as a counter in the addition to the Church, the body of Christ.  It was a way of weighing the body to see if the baby was growing properly or not.  Later in Rome when people were lined up to be baptized to make them Christians, the body was growing flabby.   When an unbeliever got baptized, the counter gave a wrong counting, but the sealing was a sealing of condemnation.  The same concept is found in the communion.  Communion is a blessing to those who receive it in faith, but a condemnation for those who partake of it unworthy. 

What does baptism do? 

For the person who is baptized, it is an initiation into the church.  If he is an adult or the head of a family or tribe or nation it is his confession of faith in Jesus Christ individually or collectively. For the outward world it is a declaration of his new identity as a member of the church and declares their allegiance to Jesus.  If we look at the history of Islam, Islam did use the national conversion method. Their baptism was the declaration starting "la ilah". This will require a change in relationships with his friends, family and community as a whole.  When a man leaves his evil ways and finds salvation, this is the way he tells his old companions that he is no more the same old man.  He thereby comes into new relations within the church - the family of God.  It protects the infant (irrespective of how old he is) by being in the family and provides an environment to grow. It is also compared to clothing, which protects from heat and cold.
 
Why do we have big marriage ceremony?  There is an announcement, and a ceremony in the midst of the community and a celebration.  All these are necessary to make sure that a new relationship has been established between the boy and the girl and they are not available for others.  A new relationship is established between other girls and boys.  Baptism also does the same.  It is important and necessary.  It has nothing to do with salvation, but everything to do with growing in maturity in faith. 

Then the mode of this ceremony and the occurrence (whether it should be public or private or concealed) depends on the communal situation.  If a public announcement destroys the person should we refrain from such public display?  When the early church was an underground church, baptism was conducted underground among the believing community.  Sometimes an open baptism becomes a powerful witnessing in situation.  We can hardly place a hard and fast rule regarding, when, where, how of the ceremony. 

Before we go into the details let us first understand what is a covenant.
Webster's New World Dictionary defines a "Covenant" or "Testament" as follows. "A binding and solemn agreement to do or keep from doing a specified thing; compact, a will, or an agreement made by or between two or more parties; orig., a covenant, esp. one between God and man; a statement, act, etc. testifying to the fact, validity, or worth of something; testimonial (©1995 Zane Publishing, Inc. ©1994, 1991, 1988 Simon & Schuster, Inc.)"

A Biblical Covenant is a contract or a promise by God with people. There is actually two major convenants. (in fact when God deals with an individual or a family or a community he makes a covenant with them). The Old Covenant given in Old Testament and the New Covenant given in the New Testament. Even though the covenant is new, both the Old and the New covenants are essentially same.

The mediator is the same: Jesus 
Acts 4:12   Salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved." 
Acts 10:43   All the prophets testify about him that everyone who believes in him receives forgiveness of sins through his name." 
1Tim. 2:5-6   For there is one God and one mediator between God and men, the man Christ Jesus, who gave himself as a ransom for all men --the testimony given in its proper time. 

At the time of Mosaic covenant, Jesus himself was present. 
Exod. 24:9-11   Moses and Aaron, Nadab and Abihu, and the seventy elders of Israel went up and saw the God of Israel. Under his feet was something like a pavement made of sapphire, clear as the sky itself. But God did not raise his hand against these leaders of the Israelites; they saw God, and they ate and drank. 

 The condition is the same- faith 
Gen. 15:6   Abram believed the LORD, and he credited it to him as righteousness. 
 Rom. 4:3   What does the Scripture say? "Abraham believed God, and it was credited to him as righteousness." 

In both cases there were seals and signs of the covenant. 

What are some of the seals of the covenants? 

In Abrahamic covenant the seal was through a sacrifice by God walking between the pieces of the sacrifice (Gen 15:17-21). In Abraham's case the election was passed on to Abraham through the Priest of the Most High, Melchizedek in a communion ceremony (Ex. 13:18) In the Mosaic covenant we read: 
Exod. 24:8   Moses then took the blood, sprinkled it on the people and said, "This is the blood of the covenant that the LORD has made with you in accordance with all these words." 

In both these events it was sealed with animal sacrifice and sprinkling of blood. The element was blood and was sprinkled. This was a historical one event.

What is this seal in the new covenant? 

Hebr. 9:19 -12:24  When Moses had proclaimed every commandment of the law to all the people, he took the blood of calves, together with water, scarlet wool and branches of hyssop, and sprinkled the scroll and all the people. ...Hebr. 9:21   In the same way, he sprinkled with the blood both the tabernacle and everything used in its ceremonies. ...Hebr. 10:22   let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water. . Hebr. 12:24   to Jesus the mediator of a new covenant, and to the sprinkled blood that speaks a better word than the blood of Abel. 

In the Old Covenant it was followed by a feast where the elders took part in the presence of Yvh (Ex 24:9-11),"leaders of the Israelites; they saw God, and they ate and drank. "In the new covenant breaking of the bread and the partaking of the Lord's table. 

The sign of the old covenant both Abrahamic and Mosaic were circumcision. 

Gen. 17:9-13   Then God said to Abraham, "As for you, you must keep my covenant, you and your descendants after you for the generations to come.   This is my covenant with you and your descendants after you, the covenant you are to keep: Every male among you shall be circumcised.  You are to undergo circumcision, and it will be the sign of the covenant between you and me. 
 
For the generations to come every male among you who is eight days old must be circumcised, including those born in your household or bought with money from a foreigner --those who are not your offspring.  Whether born in your household or bought with your money, they must be circumcised. My covenant in your flesh is to be an everlasting covenant. 
Notice here several facts: 
1.  Though Abraham was the second party in the covenant, the covenant was with him and to with his descendants.  It was communal act.  It was not only Abraham, but also the entire tribe including those born in the household and slaves bought with money, irrespective of  their faith.  It was to be done in anticipation of God's promise of salvation. 
2.  It was an external surgery and did not change his state. Yet he became eligible to the blessings of the covenant.  He did not get the blessing unless; other basic requirements are met. 
3.  Yet it was not an open sign.  Unless he was disrobed no one could know it.  It was personal.   

 Thus  baptism is the sign of the New Covenant just as circumcision was the sign and seal of the Abrahamic covenant.  A seal does not provide the validity of the document.  It attests to the origin or the person who  make the document.  It is so with baptism.  Baptism does not save; it is God who saves.   The seal declares the ownership.  We shall see later that Paul actually call baptism, the spiritual circumcision.
Circumcision was the sign of the Jewish origin.  It declared the owner as Yahweh. 
What does baptism do?  It declares that Jesus is the owner. 

Baptism is the sign and not the substance of salvation.  James says: If a man say he has faith, and has not works, can faith save him?  The important word here is "say"  There must be more than a profession. There must be reality in the soul.  A person that fully trusts Christ has the blessed assurance of salvation (Heb. 11:1)  Confessing Christ is the ongoing results and not the means of salvation. If Roman 10:9-10 is right, baptism has no role in salvation. It is the confession with tongue that matters. Declare your faith in words boldly. When the heart is filled, the mouth will speak and works will follow.

Lev. 14. The purpose? As a Proof to the People. If there is a parallel here, let us understand it.

Conversion is always a matter of the heart, which is the reality. But it is proved to the people only when it is expressed in action. The function of baptism is just that. It is a proof to the people. Jesus while he was with us asked people to go through the mikvah and other Mosaic rituals just for that purpose. All through Old Testament Leprosy was considered an analogy of sin. When Jesus healed lepers he instructed them, "Go show yourself to the priest, and offer the gift that Moses commanded, for a proof to the people" (Mat. 8:2-4; Mark 1:40-44; Luke 5:12-14) (People included even the priests) This included the elaborate ritual baptisms prescribed by Moses