30 years from when or what event? The Crucifixion and Resurrection of Jesus Christ?
The Council of Jerusalem is generally dated to
48 AD, roughly 15 to 25 years after the crucifixion of Jesus. Galatians is believed by most scholars to be written 49-50 AD.
Yet at the Council of Jerusalem in Acts 15 Peter states that both Jews and Gentiles are saved by Grace.
Acts 15: NASB
1Some men came down from Judea and began teaching the brethren, “Unless you are circumcised according to the custom of Moses, you cannot be saved.” 2And when Paul and Barnabas had great dissension and debate with them, the brethren determined that Paul and Barnabas and some others of them should go up to Jerusalem to the apostles and elders concerning this issue. 3Therefore, being sent on their way by the church, they were passing through both Phoenicia and Samaria, describing in detail the conversion of the Gentiles, and were bringing great joy to all the brethren. 4When they arrived at Jerusalem, they were received by the church and the apostles and the elders, and they reported all that God had done with them. 5But some of the sect of the Pharisees who had believed stood up, saying, “It is necessary to circumcise them and to direct them to observe the Law of Moses.”
6The apostles and the elders came together to look into this matter. 7After there had been much debate, Peter stood up and said to them, “Brethren, you know that in the early days God made a choice among you, that by my mouth the Gentiles would hear the word of the gospel and believe. 8“And God, who knows the heart, testified to them giving them the Holy Spirit, just as He also did to us; 9and He made no distinction between us and them, cleansing their hearts by faith. 10“Now therefore why do you put God to the test by placing upon the neck of the disciples a yoke which neither our fathers nor we have been able to bear? 11“But we believe that we are saved through the grace of the Lord Jesus, in the same way as they also are.”
Notice Peter is referring to a much earlier time when he preached the Gospel to the Gentiles "in the early days", that they (the Gentiles) also received the Holy Spirit (Acts 10) making no distinction "cleansing their hearts by faith." Then goes on to say both Jew and Gentile "are saved through the grace of the Lord Jesus."
Here is another example of Peter convincing the Jews that the Gentiles were saved just as they were:
Acts 11: NASB
1Now the apostles and the brethren who were throughout Judea heard that the Gentiles also had received the word of God. 2And when Peter came up to Jerusalem, those who were circumcised took issue with him, 3saying, “You went to uncircumcised men and ate with them.” 4But Peter began speaking and proceeded to explain to them in orderly sequence, saying, 5“I was in the city of Joppa praying; and in a trance I saw a vision, an object coming down like a great sheet lowered by four corners from the sky; and it came right down to me, 6and when I had fixed my gaze on it and was observing it I saw the four-footed animals of the earth and the wild beasts and the crawling creatures and the birds of the air.
7“I also heard a voice saying to me, ‘Get up, Peter; kill and eat.’ 8“But I said, ‘By no means, Lord, for nothing unholy or unclean has ever entered my mouth.’ 9“But a voice from heaven answered a second time, ‘What God has cleansed, no longer consider unholy.’ 10“This happened three times, and everything was drawn back up into the sky. 11“And behold, at that moment three men appeared at the house in which we were staying, having been sent to me from Caesarea. 12“The Spirit told me to go with them without misgivings. These six brethren also went with me and we entered the man’s house. 13“And he reported to us how he had seen the angel standing in his house, and saying, ‘Send to Joppa and have Simon, who is also called Peter, brought here;
14and he will speak words to you by which you will be saved, you and all your household.’ 15“And as I began to speak, the Holy Spirit fell upon them just as He did upon us at the beginning. 16“And I remembered the word of the Lord, how He used to say, ‘John baptized with water, but you will be baptized with the Holy Spirit.’ 17“Therefore if God gave to them the same gift as He gave to us also after believing in the Lord Jesus Christ, who was I that I could stand in God’s way?” 18When they heard this, they quieted down and glorified God, saying, “Well then, God has granted to the Gentiles also the repentance that leads to life.”
There is only One Gospel. It is Christ has died, Christ is Risen, Christ will Come Again. This is Grace. This is what Peter and the other apostles preached since Pentecost.
I think many create an unnecessary dichotomy of Gospel of the Kingdom vs. Gospel of Grace. The Gospel of the Kingdom Jesus preached before His death, Resurrection and Ascension into Heaven was one of Perfection (Matthew 5:48)
“Therefore you are to be perfect, as your heavenly Father is perfect."
In Matthew 5 Jesus preached the perfection of the Law. One must be dragged up Mount Sinai (Law) and exposed to their sin and condemnation before they can know the Salvation of Mount Zion (Grace).
The Gospel of the Kingdom is not in opposition to the Gospel of Grace. They compliment each other.
Now on Paul preaching the Gospel of the Kingdom? We see that happening even in the last chapter of Acts of the Apostles:
Acts 28: NASB
23When they had set a day for Paul, they came to him at his lodging in large numbers; and he was explaining to them by solemnly testifying about the kingdom of God and trying to persuade them concerning Jesus, from both the Law of Moses and from the Prophets, from morning until evening. 24Some were being persuaded by the things spoken, but others would not believe. 25And when they did not agree with one another, they began leaving after Paul had spoken one parting word, “The Holy Spirit rightly spoke through Isaiah the prophet to your fathers,
26saying,
‘GO TO THIS PEOPLE AND SAY,
“YOU WILL KEEP ON HEARING, BUT WILL NOT UNDERSTAND;
AND YOU WILL KEEP ON SEEING, BUT WILL NOT PERCEIVE;
27FOR THE HEART OF THIS PEOPLE HAS BECOME DULL,
AND WITH THEIR EARS THEY SCARCELY HEAR,
AND THEY HAVE CLOSED THEIR EYES;
OTHERWISE THEY MIGHT SEE WITH THEIR EYES,
AND HEAR WITH THEIR EARS,
AND UNDERSTAND WITH THEIR HEART AND RETURN,
AND I WOULD HEAL THEM.”’
28“Therefore let it be known to you that this salvation of God has been sent to the Gentiles; they will also listen.” 29[When he had spoken these words, the Jews departed, having a great dispute among themselves.]
30And he stayed two full years in his own rented quarters and was welcoming all who came to him, 31preaching the kingdom of God and teaching concerning the Lord Jesus Christ with all openness, unhindered.
Notice he preached the Kingdom and tried persuading them concerning Jesus. There you have the complimentary message, not in opposition.
