The word "gospel" means "good news." Jesus was preaching the gospel of the kingdom to Israel. John the Baptist also preached the gospel of the kingdom, which was, "..Repent, for the kingdom of heaven is at hand" (Matthew 3:2).
Jesus Christ sent the twelve to preach only to Israel. Matthew 10:5 - These twelve Jesus sent out and commanded them, saying: “Do not go into the way of the Gentiles, and do not enter a city of the Samaritans. 6 But go rather to the lost sheep of the house of Israel. 7 And as you go, preach, saying, 'The kingdom of heaven is at hand.' The disciples were specifically told to go only to the people of Israel, and they were not yet preaching anything about the death, burial, and resurrection of Christ.
In Matthew 16:15, Jesus Christ asked His disciples, “But who do you say that I am?” 16 Simon Peter answered and said, "You are the Christ, the Son of the living God." 17 Jesus answered and said to him, “Blessed are you, Simon Bar-Jonah, for flesh and blood has not revealed this to you, but My Father who is in heaven.
Now Peter had no clue yet that Jesus Christ would be crucified, buried and resurrected, but he truly believed that Jesus was the Messiah. This is obvious when, only moments later, Peter rebukes Jesus Christ for saying he will be killed, and be raised again the third day" (Matthew 16:21). In verse 22, "..Peter took him and began to rebuke him, saying, “Far be it from You, Lord; this shall not happen to You!”
Before his death, Jesus told the twelve that He had to die and that he would rise on the third day. Looking back on this passage of scripture, we see Jesus speaking of an event that would change the world! However, it's obvious that the disciples were ignorant of its meaning.
Then he took unto him the twelve, and said unto them, Behold, we go up to Jerusalem,.. And they shall scourge him, and put him to death: and the third day he shall rise again. And they understood none of these things: and this saying was hid from them, neither knew they the things which were spoken. – Luke 18:31-34. hmm... that's strange if the content of the gospel that came through a revelation of Jesus Christ to Paul and was a mystery prior to that has the same content as the gospel of the kingdom. *This is where we need to RIGHTLY DIVIDE THE WORD OF TRUTH.
After his crucifixion, instead of anxiously waiting his resurrection, the apostles were still ignorant and disheartened at the death of their Messiah, and did not even at first believe the testimony of his resurrection (Mark 16:14, Luke 24:19-24).
It was not until after his resurrection that Jesus appeared to the apostles and opened their understanding (Luke 24:44-47).
In 1 Corinthians 15:1-4, we read that the gospel is the "good news" of the death, burial and resurrection of Christ and in Romans 1:16, we see that it's the power of God unto salvation to everyone that believes.. After the cross, there is a distinct element to the content of the gospel which is called "the mystery of the gospel" (see Ephesians 6:19 and Colossians 1:26-27; 4:3). This new revelation that the apostle Paul received from Jesus (Galatians 1:11-12) is that the Gentiles are fellow heirs and fellow members of the same body (the body of Christ) and fellow partakers of the promise (Ephesians 3:1-9). Jews and Gentiles are now united together in one body and this was previously a mystery. The distinct message of the church is that Jews and Gentiles alike may believe the gospel and be united together into ONE BODY (Ephesians 1:13; 1 Corinthians 12:13).
