6 I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:
7 Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.
8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
9 As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.
10 For do I now persuade men, or God? or do I seek to please men? for if I yet pleased men, I should not be the servant of Christ.
Gal. 1:6–10.
Two different Greek words translated by one English word "another."
Strong's: [G#2087] "another" (vs. 6)
Greek Word: ἕτερος
Transliteration: heteros
Meaning: other or different.
Application: you have five ink pens. They are all five ink pens but each one is a Bic, Pentel, Parker, Cross, and a Paper Mate. Five ink pens of a different kind.
Strong's: [G#243] "another" (vs. 7)
Greek Word: ἄλλος
Transliteration: allos
Meaning: a primary word; “else,” i.e. different (in many applications)
Application: You have five ink pens. All five are Bic ink pens. Five Bic ink pens of the same kind.
Saul/Paul was a Pharisee in the Jewish Sanhedrin. He was a priest in the Jews religion. The Jews religion consisted of covenants, promises, prophecies contained in the Hebrew/Jewish Scriptures of their Law, their Psalms, and their Prophets, also known as the First Covenant Scriptures.
On the day of the Jewish Feast of Harvest (Pentecost) in Jerusalem where God commanded all Jewish males attend three feasts in the Law.
At this Feast 3000 Jews were born again and saved by God and given the Holy Spirit as fulfillment of the Jeremian Jewish New Covenant described in Jeremiah 31:31-34. Jews from all over Gentiles lands came to Jerusalem to this feast and when the celebration was over returned to their homes in Gentile lands and as a result were the founders of the Jewish Church and churches in Jerusalem and in cities and towns such as Corinth, Ephesus, Thessalonica, Philippi, and even Rome. The took their experiences, an outline of Peter's sermon, and Jesus with them back to their synagogues to their Jewish brethren that did not attend the feast in Jerusalem. Peter's sermon in Acts 2 addressed the advent of the Promised Holy Spirit and prophecies from Joel and David, and others, so, they knew that what transpired was Jewish in nature and related to their religion under the Abrahamic and Mosaic Covenants as well as the Scriptures of their prophets. It was the beginning of a "New" thing God was doing in the earth with regard to His Covenant people Israel. They had their own Scriptures of the Law, the Psalms, and the Prophets to try to make sense of it. Let's be clear about this. What happen on Pentecost happened to Jews only. This was before Saul/Paul became a Christian. This event and the years that followed were solely a Jewish phenomenon and all the Jews had been their own Scriptures to understand what God was doing with His Covenant people Israel.
In the beginning even up to the destruction of their Temple in A.D. 70 everything was witnessed through the lens of the Jewish Scriptures. As part of the Abrahamic Covenant God required all males to undergo circumcision. This was a sign of the Covenant with Abraham. Around A.D. 37 Saul/Paul became a Christ-follower and after initially visiting the Jewish synagogues wherever he went he took a 3-year 'Sabbatical' and also went into Arabia for 14 years. By the time of his travels with Barnabas (Acts 13) Judaism had become entrenched in the beginning of the first two decades after Pentecost with understanding the New Covenant that was taking place with the Jewish people. Soon, about 20 years after Pentecost Paul went into Gentile lands and to the synagogues to 'preach' and 'teach' as Pharisee that Israel's Messiah was in the person of Jesus bar Joseph. When he returned from his travels, he wrote to Jewish Christians the letters we now have as part of the New Covenant canon. One of the things Saul/Paul addressed in his letters was how to deal with Gentiles who became saved and received the Promised to Israel Holy Spirit. Peter may have been involved in the conversion of Cornelius in Acts 10 but he, James, John, and the rest of the apostles applied a Jewish influence in their understanding of the New Covenant and agreed that for the most part any Gentile who became converted to the New Covenant had to be circumcised. Galatians 2 records Saul/Paul taking issue with Peter's hypocrisy and rebuked his behavior in front of everybody.
Now, I said all that and I can say more, but to respond to your question(s) concerning Galatians 1:6-10, what Saul/Paul is saying is that:
6 I marvel that ye are so soon removed from him that called you into the grace of Christ unto another [of a different kind - Judaism] gospel:
7 Which is not another [of the same kind - Christianity]; but there be some that trouble you [Peter, James], and would pervert the gospel of Christ.
8 But though we, or an angel from heaven, preach any other gospel [Judaism] unto you than that which we have preached unto you [Christianity], let him be accursed.
9 As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.
10 For do I now persuade men, or God? or do I seek to please men? for if I yet pleased men, I should not be the servant of Christ.
Godslittleservant:
Q: My question is what is the gospel that they have preached to us?
A: The gospel [good news] is about Israel's Messiah and His effect upon the Abrahamic and Mosaic and New Covenants. The New Covenant found in Jeremiah 31:31-34.
Q: Who is the we?
A: It is well supposed the "we" are Saul/Paul and Barnabas.
Q: Is Peter and Paul preaching the same gospel or different gospels?
A: No, not at the beginning. Peter was a fisherman by trade and did not have access to the Jewish Scriptures. Saul/Paul on the other hand had books and parchments and as Pharisee in the Jews religion had ready access to the Jewish Scriptures and spent his adult life reading and studying those Scriptures and was well versed. The problem was he only understood the letter of the Law until his conversion and the Holy Spirit in time illuminated the Seed of the Word of God he'd plant in his soul all those many years as Pharisee. And along with spending about 13-17 years before his travels spent that time trying to understand what was going on after Pentecost and the advent of the Holy Spirit and Jesus' effect He had on the Jewish covenants. What Saul/Paul began to understand was what Jesus had been teaching all along and that was the spirit of the Law.
Q: Can this gospel be found in the bible?
A: You're going to have to do just as what Saul/Paul had done this gospel [good news] about Israel's Messiah and search the Scriptures. The answer can be found throughout the Jewish Scriptures of the Law, the Psalms, and the Prophets. There is no one verse that can encapsulate everything having to do with the covenants and the promises and the prophecies in the Jewish writings about Israel's Messiah.
Q: Book Chapter and verse?
A: ibid.
As a matter of instruction, the New Covenant writings of Saul/Paul, Peter, James, Jude, John, were written by Jewish Christians to and for other Jewish Christians and merely discuss what is found in the Jewish writings of the Law, the Psalms, and the Prophets. It is important that their writings be found to be saying the same things as God had said in the First Covenant. Keep in mind that there is no covenant in these writings but that the writers are discussing the things contained in the Jewish Scriptures such as the Jewish covenants, promises, and prophecies about Israel's Messiah, Redeemer, and King.