Please explain what you mean by Gospel messages. I consider the Gospel messages to be the entire New Testament which would make your statement untrue.
The apostles didn’t have the entire New Testament. They didn’t have Catholic tradition or anything else that followed. They only had “believe in Jesus and be baptized.”
Mark 16:14 Afterward He appeared to the eleven themselves as they were reclining at the table; and He reproached them for their unbelief and hardness of heart, because they had not believed those who had seen Him after He had risen. 1
5And He said to them, “Go into all the world and preach the gospel to all creation. 16“He who has believed and has been baptized shall be saved; but he who has disbelieved shall be condemned. 17“These signs will accompany those who have believed: in My name they will cast out demons, they will speak with new tongues; 18they will pick up serpents, and if they drink any deadly poison, it will not hurt them; they will lay hands on the sick, and they will recover.”
Jesus preaches the gospel
John 3:16“For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life. 17“For God did not send the Son into the world to judge the world, but that the world might be saved through Him.
18“He who believes in Him is not judged; he who does not believe has been judged already, because he has not believed in the name of the only begotten Son of God. 19“This is the judgment, that the Light has come into the world, and men loved the darkness rather than the Light, for their deeds were evil. 20“For everyone who does evil hates the Light, and does not come to the Light for fear that his deeds will be exposed. 21“But he who practices the truth comes to the Light, so that his deeds may be manifested as having been wrought in God.”
Acts 8:34The eunuch answered Philip and said, “Please tell me, of whom does the prophet say this? Of himself or of someone else?”
35Then Philip opened his mouth, and beginning from this Scripture he preached Jesus to him. 36As they went along the road they came to some water; and the eunuch said, “Look! Water! What prevents me from being baptized?”
Acts 10:34 Opening his mouth, Peter said:
“I most certainly understand now that God is not one to show partiality, 35but in every nation the man who fears Him and does what is right is welcome to Him. 36“The word which He sent to the sons of Israel, preaching peace through Jesus Christ (He is Lord of all)— 37you yourselves know the thing which took place throughout all Judea, starting from Galilee, after the baptism which John proclaimed. 38“You know of Jesus of Nazareth, how God anointed Him with the Holy Spirit and with power, and how He went about doing good and healing all who were oppressed by the devil, for God was with Him. 39“We are witnesses of all the things He did both in the land of the Jews and in Jerusalem. They also put Him to death by hanging Him on a cross. 40“God raised Him up on the third day and granted that He become visible, 41not to all the people, but to witnesses who were chosen beforehand by God, that is, to us who ate and drank with Him after He arose from the dead.
42“And He ordered us to preach to the people, and solemnly to testify that this is the One who has been appointed by God as Judge of the living and the dead. 43“Of Him all the prophets bear witness that through His name everyone who believes in Him receives forgiveness of sins.”
Acts 16:25 But about midnight Paul and Silas were praying and singing hymns of praise to God, and the prisoners were listening to them; 26and suddenly there came a great earthquake, so that the foundations of the prison house were shaken; and immediately all the doors were opened and everyone’s chains were unfastened. 27When the jailer awoke and saw the prison doors opened, he drew his sword and was about to kill himself, supposing that the prisoners had escaped. 28But Paul cried out with a loud voice, saying, “Do not harm yourself, for we are all here!” 29And he called for lights and rushed in, and trembling with fear he fell down before Paul and Silas, 30and after he brought them out, he said,
“Sirs, what must I do to be saved?” 31They said, “Believe in the Lord Jesus, and you will be saved, you and your household.” 32And they spoke the word of the Lord to him together with all who were in his house. 33And he took them that very hour of the night and washed their wounds, and immediately he was baptized, he and all his household. 34And he brought them into his house and set food before them, and rejoiced greatly, having believed in God with his whole household.
And your own interpretation of the Bible?