The Response
It is intuitively obvious that the response to the gospel follows from the proclamation of the gospel.  One interesting observation is that there are two elements of the response. These might be described as the "immediate response" and the "subsequent response." People who accepted the gospel were first converted, and then lived according to that faith. This practice of the early church is seen in the "Great Commission" of Matthew 28:18-19, as it speaks of the process of discipling the nations-- first "baptizing them" and then "teaching them to obey."

Faith
The starting point for any response to the gospel is acceptance of the message. Belief was so foundational that early Christians were known by their belief in Jesus and the gospel.

And all those who had believed were together, and had all things in common. (Acts 2:44)

But many of those who had heard the message believed; and the number of the men came to be about five thousand. (Acts 4:4)

And the congregation of those who believed were of one heart and soul; and not one of them claimed that anything belonging to him was his own; but all things were common property to them. (Acts 4:32)

This trait has sometimes led people to conclude that faith was all that mattered. However, the Scriptures do not support the idea that "belief alone" constituted conversion in the early church. While faith was foundational, the record of Scripture shows that their conversion experiences consisted of more than faith or simple mental assent.

Nevertheless, no one should over-react to the "faith only" (mental assent) distortion with an opposite distortion that overemphasizes other factors, nor should we minimize the place of faith in the conversion process. In the early church, belief assured that all other elements would follow. Without belief, nothing else mattered. Faith is truly the starting point in the process.

Any further response to the gospel is only relevant to those who accept or believe the proclamation:

But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name, [13] who were born not of blood, nor of the will of the flesh, nor of the will of man, but of God (John 1:12).

And he called for lights and rushed in and, trembling with fear, he fell down before Paul and Silas, [30] and after he brought them out, he said, "Sirs, what must I do to be saved?" [31] And they said, "Believe in the Lord Jesus, and you shall be saved, you and your household." [32] And they spoke the word of the Lord to him together with all who were in his house. [33] And he took them that very hour of the night and washed their wounds, and immediately he was baptized, he and all his household. [34] And he brought them into his house and set food before them, and rejoiced greatly, having believed in God with his whole household. (Acts 16:29-34)

The Immediate Response: Repentance and Baptism
The expected immediate response of the gospel proclamation was repentance and baptism. This is specified in the first proclamation of the gospel in Acts 2:
And Peter said to them, "Repent, and let each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. [39] "For the promise is for you and your children, and for all who are far off, as many as the Lord our God shall call to Himself." (Acts 2:38-39)
Repentance
At conversion, repentance was not of any particular "sins" as much as it was a turning towards Jesus and making him "Lord" or master (ref. Romans 10:9 et. al.). It was a renouncing of all other ways in favor of His way and follows as a logical response to believing the truth of the gospel-- if something is true, it must be reckoned with and acted upon.

This is not to say that repentance of individual, specific sins didn't occur. But what was far more important was a change in attitude concerning sin; indeed, the Greek term for repentance (metanoia) literally means "change of mind." Conversion was thus reckoned as a "death to sin."

What shall we say then? Are we to continue in sin that grace might increase? [2] May it never be! How shall we who died to sin still live in it? (Romans 6:1-2)
The Scriptures indicate that repentance from sin was continually necessary, as an implication of this initial death to sin.  For example, the Christians in Colosse were urged to put certain sins to death, even though they had already been converted. Similarly, the Ephesians repented of practices associated with magic after their conversion:
Therefore consider the members of your earthly body as dead to immorality, impurity, passion, evil desire, and greed, which amounts to idolatry. [6] For it is on account of these things that the wrath of God will come, [7] and in them you also once walked, when you were living in them. [8] But now you also, put them all aside: anger, wrath, malice, slander, and abusive speech from your mouth. (Colossians 3:5-8)

Many also of those who had believed kept coming, confessing and disclosing their practices. [19] And many of those who practiced magic brought their books together and began burning them in the sight of all; and they counted up the price of them and found it fifty thousand pieces of silver. (Acts 19:18-19)

This shows that repenting of specific sins was not a single action at the time of conversion. Rather, conversion was the beginning of the process by which Christians grew to become more holy (or set apart) for God's purposes:
Therefore, having these promises, beloved, let us cleanse ourselves from all defilement of flesh and spirit, perfecting holiness in the fear of God. (2 Cor 7:1)

But you did not learn Christ in this way, [21] if indeed you have heard Him and have been taught in Him, just as truth is in Jesus, [22] that, in reference to your former manner of life, you lay aside the old self, which is being corrupted in accordance with the lusts of deceit, [23] and that you be renewed in the spirit of your mind, [24] and put on the new self, which in the likeness of God has been created in righteousness and holiness of the truth. (Ephesians 4:20-24)

Baptism
Baptism was the only truly visible part of the initial response. It was not separated from the conversion process, it was an integral part of it. Through baptism, the candidate shared in the death, burial and resurrection of Jesus, had his sins forgiven or "washed away," and received the gift of the indwelling Holy Spririt. This was reckoned as the point in time when people were saved:
"Therefore let all the house of Israel know for certain that God has made Him both Lord and Christ--this Jesus whom you crucified." Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, "Brethren, what shall we do?" [38] And Peter said to them, "Repent, and let each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. "For the promise is for you and your children, and for all who are far off, as many as the Lord our God shall call to Himself." [40] And with many other words he solemnly testified and kept on exhorting them, saying, "Be saved from this perverse generation!" [41] So then, those who had received his word were baptized; and there were added that day about three thousand souls. (Acts 2:36-41)

But when they believed Philip preaching the good news about the kingdom of God and the name of Jesus Christ, they were being baptized, men and women alike (Acts 8:12).

And Crispus, the leader of the synagogue, believed in the Lord with all his household, and many of the Corinthians when they heard were believing and being baptized. (Acts 18:8)

And now why do you delay? Arise, and be baptized, and wash away your sins, calling on His name. (Acts 22:16)

What shall we say then? Are we to continue in sin that grace might increase? [2] May it never be! How shall we who died to sin still live in it? [3] Or do you not know that all of us who have been baptized into Christ Jesus have been baptized into His death? [4] Therefore we have been buried with Him through baptism into death, in order that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life.  (Romans 6:1-4)

And corresponding to that, baptism now saves you--not the removal of dirt from the flesh, but an appeal to God for a good conscience--through the resurrection of Jesus Christ. (1 Peter 3:21)

This was also known as "new birth" or being "born again" (1 Peter 1:3, 1:23, 1 John 2:21, 3:9 et. al.). By the faithful response of repentance and baptism, the convert was also added to the church (Acts 2:41).

The Subsequent Response: Learning and Obeying
Beyond the immediate response to the gospel, the early Christians changed their outlook and lifestyle based upon the truth of the gospel. This is nicely summarized in the Great Commission "... teaching them to obey everything I have commanded" (Matthew 28:19).

This subsequent response of the gospel follows logically from the immediate response. If one believes Jesus is the Son of God and repents and is baptized in His name, the next logical step is learning and following what He taught. This pattern of learning and obeying is seen in the early church:

And they were continually devoting themselves to the apostles' teaching and to fellowship, to the breaking of bread and to prayer.(Acts 2:42)

I, therefore, the prisoner of the Lord, entreat you to walk in a manner worthy of the calling with which you have been called, [2] with all humility and gentleness, with patience, showing forbearance to one another in love, [3] being diligent to preserve the unity of the Spirit in the bond of peace.(Ephesians 4:1-3)

Therefore also we have as our ambition, whether at home or absent, to be pleasing to Him. [10] For we must all appear before the judgment seat of Christ, that each one may be recompensed for his deeds in the body, according to what he has done, whether good or bad. (2 Corinthians 5:9-10)

Inasmuch as many have undertaken to compile an account of the things accomplished among us, [2] just as those who from the beginning were eyewitnesses and servants of the word have handed them down to us, [3] it seemed fitting for me as well, having investigated everything carefully from the beginning, to write it out for you in consecutive order, most excellent Theophilus; [4] so that you might know the exact truth about the things you have been taught.(Luke 1:1-4)

Thus, early Christians had a subsequent response to the gospel as well as an immediate response. They spent the rest of their lives learning to obey what Jesus taught. This addressed all areas of their lives: Copyright © 2002 John Engler. All rights reserved.
Scripture Taken from the NEW AMERICAN STANDARD BIBLE, Copyright © 1960- 1995 by the Lockman Foundation.