One of the key changes was obscuring the identity of John the Baptist by calling him John-Mark. This is because originally John the Baptist was not killed in the storyline, he was merely tested by Satan and "driven from the path".
The idea that John the Baptist was "driven from the path", like most elements of the story line, originated in the narrative about Paul.
Recovering the story about John:
In the original story about Paul's ministry begins with Paul's persecution of the worshipers of Jesus, followed by his vision and conversion. Then Paul sets out on his own ministry, where he encounters John the Baptist. But the writer of canonical Acts had to obscure the identity of John, because by the time of the writing of canonical Acts, John had been killed off in the Gospel story line.
We are first introduced to this John in Acts 12, after Peter escapes from prison:
6 The very night before Herod was going to bring him out, Peter, bound with two chains, was sleeping between two soldiers, while guards in front of the door were keeping watch over the prison. 7 Suddenly an angel of the Lord appeared, and a light shone in the cell. He tapped Peter on the side and woke him, saying, “Get up quickly.” And the chains fell off his wrists. 8 The angel said to him, “Fasten your belt and put on your sandals.” He did so. Then he said to him, “Wrap your cloak around you and follow me.” 9 Peter went out and followed him; he did not realize that what was happening with the angel’s help was real; he thought he was seeing a vision. 10 After they had passed the first and the second guard, they came before the iron gate leading into the city. It opened for them of its own accord, and they went outside and walked along a lane, when suddenly the angel left him. 11 Then Peter came to himself and said, “Now I am sure that the Lord has sent his angel and rescued me from the hands of Herod and from all that the Jewish people were expecting.”
12 As soon as he realized this, he went to the house of Mary, the mother of John whose other name was Mark, where many had gathered and were praying.
12 As soon as he realized this, he went to the house of Mary, the mother of John whose other name was Mark, where many had gathered and were praying.
This part is invented by the canonical writer in order to introduce the idea that this John is not John the Baptist.
Later we read:
24 But the word of God continued to advance and gain adherents. 25 Then after completing their mission Barnabas and Saul returned to Jerusalem and brought with them John, whose other name was Mark.
The original account of Paul meeting John has been lost.
4 So, being sent out by the Holy Spirit, they went down to Seleucia, and from there they sailed to Cyprus. 5 When they arrived at Salamis, they proclaimed the word of God in the Jewish synagogues. And they had John also to assist them.
This tells of a source of division, but also engages in some very strange revision:
13 Then Paul and his companions set sail from Paphos and came to Perga in Pamphylia. John, however, left them and returned to Jerusalem, 14 but they went on from Perga and came to Antioch in Pisidia. And on the Sabbath day they went into the synagogue and sat down. 15 After the reading of the Law and the Prophets, the officials of the synagogue sent them a message, saying, “Brothers, if you have any word of exhortation for the people, give it.” 16 So Paul stood up and with a gesture began to speak:
“Fellow Israelites and others who fear God, listen. 17 The God of this people Israel chose our ancestors and made the people great during their stay in the land of Egypt, and with uplifted arm he led them out of it. 18 For about forty years he put up with them in the wilderness. 19 After he had destroyed seven peoples in the land of Canaan, he gave them their land as an inheritance 20 for about four hundred fifty years. After that he gave them judges until the time of the prophet Samuel. 21 Then they asked for a king, and God gave them Saul son of Kish, a man of the tribe of Benjamin, who reigned for forty years. 22 When he had removed him, he made David their king. In his testimony about him he said, ‘I have found David, son of Jesse, to be a man after my heart, who will carry out all my wishes.’ 23 Of this man’s posterity God has brought to Israel a Savior, Jesus, as he promised; 24 before his coming John had already proclaimed a baptism of repentance to all the people of Israel. 25 And as John was finishing his work, he said, ‘What do you suppose that I am? I am not he. No, but one is coming after me; I am not worthy to untie the strap of the sandals on his feet.’
“Fellow Israelites and others who fear God, listen. 17 The God of this people Israel chose our ancestors and made the people great during their stay in the land of Egypt, and with uplifted arm he led them out of it. 18 For about forty years he put up with them in the wilderness. 19 After he had destroyed seven peoples in the land of Canaan, he gave them their land as an inheritance 20 for about four hundred fifty years. After that he gave them judges until the time of the prophet Samuel. 21 Then they asked for a king, and God gave them Saul son of Kish, a man of the tribe of Benjamin, who reigned for forty years. 22 When he had removed him, he made David their king. In his testimony about him he said, ‘I have found David, son of Jesse, to be a man after my heart, who will carry out all my wishes.’ 23 Of this man’s posterity God has brought to Israel a Savior, Jesus, as he promised; 24 before his coming John had already proclaimed a baptism of repentance to all the people of Israel. 25 And as John was finishing his work, he said, ‘What do you suppose that I am? I am not he. No, but one is coming after me; I am not worthy to untie the strap of the sandals on his feet.’
What I think has happened here is that in the original story John left Paul and went to Jerusalem. There, John gave the speech that is now in the mouth of Paul. The original was probably something more like:
13 Then Paul and his companions set sail from Paphos and came to Perga in Pamphylia. John, however, left them and returned to Jerusalem, 14 but they went on from Perga and came to Antioch in Pisidia. On the Sabbath day John went into the synagogue and sat down. 15 After the reading of the Law and the Prophets, the officials of the synagogue sent them a message, saying, “Brothers, if you have any word of exhortation for the people, give it.” 16 So John stood up and with a gesture began to speak:
“Fellow Israelites and others who fear God, listen. 17 The God of this people Israel chose our ancestors and made the people great during their stay in the land of Egypt, and with uplifted arm he led them out of it. 18 For about forty years he put up with them in the wilderness. 19 After he had destroyed seven peoples in the land of Canaan, he gave them their land as an inheritance 20 for about four hundred fifty years. After that he gave them judges until the time of the prophet Samuel. 21 Then they asked for a king, and God gave them Saul son of Kish, a man of the tribe of Benjamin, who reigned for forty years. 22 When he had removed him, he made David their king. In his testimony about him he said, ‘I have found David, son of Jesse, to be a man after my heart, who will carry out all my wishes.’ 23 Of this man’s posterity God will bring to Israel a Savior, Jesus, as he promised; 24 before his coming John proclaimed a baptism of repentance to all the people of Israel. 25 And as John was finishing his work, he said, ‘What do you suppose that I am? I am not he. No, but one is coming after me; I am not worthy to untie the strap of the sandals on his feet.’[/u]
“Fellow Israelites and others who fear God, listen. 17 The God of this people Israel chose our ancestors and made the people great during their stay in the land of Egypt, and with uplifted arm he led them out of it. 18 For about forty years he put up with them in the wilderness. 19 After he had destroyed seven peoples in the land of Canaan, he gave them their land as an inheritance 20 for about four hundred fifty years. After that he gave them judges until the time of the prophet Samuel. 21 Then they asked for a king, and God gave them Saul son of Kish, a man of the tribe of Benjamin, who reigned for forty years. 22 When he had removed him, he made David their king. In his testimony about him he said, ‘I have found David, son of Jesse, to be a man after my heart, who will carry out all my wishes.’ 23 Of this man’s posterity God will bring to Israel a Savior, Jesus, as he promised; 24 before his coming John proclaimed a baptism of repentance to all the people of Israel. 25 And as John was finishing his work, he said, ‘What do you suppose that I am? I am not he. No, but one is coming after me; I am not worthy to untie the strap of the sandals on his feet.’[/u]
Here we see that John leaves Paul and starts to proclaim his own message of repentance. Here, John is talking about the coming of Jesus in the future.
In the meantime Paul had returned to Jerusalem with Barnabas. Then we read:
36 After some days Paul said to Barnabas, “Come, let us return and visit the brothers and sisters in every city where we proclaimed the word of the Lord and see how they are doing.” 37 Barnabas wanted to take with them John called Mark. 38 But Paul decided not to take with them one who had deserted them in Pamphylia and had not accompanied them in the work. 39 The disagreement became so sharp that they parted company; Barnabas took Mark [John] with him and sailed away to Cyprus. 40 But Paul chose Silas and set out, the brothers and sisters commending him to the grace of the Lord. 41 He went through Syria and Cilicia, strengthening the churches.
So here is where the split between Paul and John the Baptist is solidified and their conflict is clarified.
Now in Acts 18 we read:
24 Now there came to Ephesus a Jew named Apollos from Alexandria. He was an eloquent man, well-versed in the scriptures. 25 He had been instructed in the Way of the Lord, and he spoke with burning enthusiasm and taught accurately the things concerning Jesus, though he knew only the baptism of John. 26 He began to speak boldly in the synagogue, but when Priscilla and Aquila heard him they took him aside and explained the Way of God to him more accurately. 27 And when he wished to cross over to Achaia, the brothers and sisters encouraged him and wrote to the disciples to welcome him.
...
19:1 While Apollos was in Corinth, Paul passed through the interior regions and came to Ephesus, where he found some disciples. 2 He said to them, “Did you receive the Holy Spirit when you became believers?” They replied, “No, we have not even heard that there is a Holy Spirit.” 3 Then he said, “Into what, then, were you baptized?” They answered, “Into John’s baptism.” 4 Paul said, “John baptized with the baptism of repentance, telling the people to believe in the one who was to come after him, that is, in Jesus.” 5 On hearing this, they were baptized in the name of the Lord Jesus. 6 When Paul had laid his hands on them, the Holy Spirit came upon them, and they spoke in tongues and prophesied, 7 altogether there were about twelve of them.
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19:1 While Apollos was in Corinth, Paul passed through the interior regions and came to Ephesus, where he found some disciples. 2 He said to them, “Did you receive the Holy Spirit when you became believers?” They replied, “No, we have not even heard that there is a Holy Spirit.” 3 Then he said, “Into what, then, were you baptized?” They answered, “Into John’s baptism.” 4 Paul said, “John baptized with the baptism of repentance, telling the people to believe in the one who was to come after him, that is, in Jesus.” 5 On hearing this, they were baptized in the name of the Lord Jesus. 6 When Paul had laid his hands on them, the Holy Spirit came upon them, and they spoke in tongues and prophesied, 7 altogether there were about twelve of them.
Here is the crux. Paul's baptism was a baptism into the death of Jesus through the holy spirit. According to Paul, baptism was a process of rebirth into the new life with Jesus. According to John, baptism was a repentance for sin in preparation for the coming of Jesus. The story indicated that Paul's ministry was superior to John's ministry.
It is from this background that the introduction of the Gospel narrative was derived, in which John is engaged in a baptism for the repentance for sins and then Jesus comes.
So the narrative about Paul and John with their competing ministries existed first. The writer of proto-Mark mark then built on this existing story.
The writer of proto-Mark was pro-Paul and thus wrote the beginning of his story like this:
2 As it is written in the prophets,
“See, I am sending my messenger ahead of you,
who will prepare your way,
3 the voice of one crying out in the wilderness:
‘Prepare the way of the Lord;
make his paths straight,’ ”
4 so John the baptizer appeared in the wilderness, proclaiming a baptism of repentance for the forgiveness of sins. 5 And the whole Judean region and all the people of Jerusalem were going out to him and were baptized by him in the River Jordan, confessing their sins. 6 Now John was clothed with camel’s hair, with a leather belt around his waist, and he ate locusts and wild honey. 7 He proclaimed, “The one who is more powerful than I is coming after me; I am not worthy to stoop down and untie the strap of his sandals. 8 I have baptized you with water, but he will baptize you with the Holy Spirit.”
9 In those days Jesus came from Galilee and baptized John in the Jordan. 10 And just as he was coming up out of the water, he saw the heavens torn apart and the Spirit descending like a dove upon him. 11 And a voice came from the heavens, “This is my Son, the Beloved; with Him I am well pleased.”
12 And the Spirit immediately drove him out into the wilderness. 13 He was in the wilderness forty days, tested by Satan, and he was with the wild beasts, and the angels waited on him.
14 Now after John was delivered up (to Satan), Jesus came to Galilee proclaiming the good news of God 15 and saying, “The time is fulfilled, and the kingdom of God has come near; repent, and believe in the good news.”
“See, I am sending my messenger ahead of you,
who will prepare your way,
3 the voice of one crying out in the wilderness:
‘Prepare the way of the Lord;
make his paths straight,’ ”
4 so John the baptizer appeared in the wilderness, proclaiming a baptism of repentance for the forgiveness of sins. 5 And the whole Judean region and all the people of Jerusalem were going out to him and were baptized by him in the River Jordan, confessing their sins. 6 Now John was clothed with camel’s hair, with a leather belt around his waist, and he ate locusts and wild honey. 7 He proclaimed, “The one who is more powerful than I is coming after me; I am not worthy to stoop down and untie the strap of his sandals. 8 I have baptized you with water, but he will baptize you with the Holy Spirit.”
9 In those days Jesus came from Galilee and baptized John in the Jordan. 10 And just as he was coming up out of the water, he saw the heavens torn apart and the Spirit descending like a dove upon him. 11 And a voice came from the heavens, “This is my Son, the Beloved; with Him I am well pleased.”
12 And the Spirit immediately drove him out into the wilderness. 13 He was in the wilderness forty days, tested by Satan, and he was with the wild beasts, and the angels waited on him.
14 Now after John was delivered up (to Satan), Jesus came to Galilee proclaiming the good news of God 15 and saying, “The time is fulfilled, and the kingdom of God has come near; repent, and believe in the good news.”
This is then confirmed in the Parable of the Sower:
13 And he said to them, “Do you not understand this parable? Then how will you understand all the parables? 14 The sower sows the word. 15 These are the ones on the path where the word is sown: when they hear, Satan immediately comes and takes away the word that is sown in them. 16 And these are the ones sown on rocky ground: when they hear the word, they immediately receive it with joy. 17 But they have no root and endure only for a while; then, when trouble or persecution arises on account of the word, immediately they fall away. 18 And others are those sown among the thorns: these are the ones who hear the word, 19 but the cares of the age and the lure of wealth and the desire for other things come in and choke the word, and it yields nothing. 20 And these are the ones sown on the good soil: they hear the word and accept it and bear fruit, thirty and sixty and a hundredfold.”
John is the one on the path where the word was sown. Satan immediately came and took away the word that was sown in him.
Why does the writer of proto-Mark say this? Because unlike Paul, John did not teach that Jesus was to, "to give his life a ransom for many." The writer of proto-Mark views Paul as the only legitimate apostle.