According to mainstream Christianity, the gospel is the good news that Jesus Christ, the Son of God, died for our sins and rose again, that those who believe in Him might receive eternal life.  It is absolutely true that Christ died for our sins that we might receive eternal life; however, it is only part of the gospel that Jesus Christ and His disciples preached.

Let’s take a closer look at what the full gospel is.

The gospel of the kingdom of God

The word gospel is translated from the Greek euaggelion which means “good news, good message”.  The term “good message” is interesting because it makes the person giving the message “a messenger”.  The prophet Malachi wrote of God sending two messengers.

Mal 3:1  “Behold, I send My messenger [John the Baptist], And he will prepare the way before Me. And the Lord, whom you seek, Will suddenly come to His temple, Even the Messenger of the covenant, In whom you delight. Behold, He is coming,” Says the LORD of hosts.

The first messenger mentioned is clearly John the Baptist as explained by Jesus Christ, when He quoted from Malachi 3:1 in reference to John the Baptist.

Mat 11:7  As they departed, Jesus began to say to the multitudes concerning John: “What did you go out into the wilderness to see? A reed shaken by the wind?
Mat 11:8  But what did you go out to see? A man clothed in soft garments? Indeed, those who wear soft clothing are in kings’ houses.
Mat 11:9  But what did you go out to see? A prophet? Yes, I say to you, and more than a prophet.
Mat 11:10  For this is he of whom it is written: ‘BEHOLD, I SEND MY MESSENGER BEFORE YOUR FACE, WHO WILL PREPARE YOUR WAY BEFORE YOU.’
Mat 11:11  “Assuredly, I say to you, among those born of women there has not risen one greater than John the Baptist; but he who is least in the kingdom of heaven is greater than he.

The second messenger mentioned, “the Messenger of the covenant” is Jesus Christ, who brought the message about the New Covenant.  The point is that Jesus Christ was, among other things, a messenger bringing a message from God the Father.  Acts 10 provides some details about this message.

Act 10:36  The word which God sent to the children of Israel, preaching peace through Jesus Christ—He is Lord of all—
Act 10:37  that word you know, which was proclaimed throughout all Judea, and began from Galilee after the baptism which John preached:

The details given about the message regard by whom (God), to whom (the children of Israel), through whom (Jesus Christ), and where (first preached in Galilee and then throughout Judea).

This ties in with the beginning of Mark which tells us that Jesus Christ (the “whom” of Acts 10:36-37) came to Galilee (the “where” of Acts 10:36-37) and started preaching the gospel.

Mar 1:14  Now after John was put in prison, Jesus came to Galilee, preaching the gospel of the kingdom of God,
Mar 1:15  and saying, “The time is fulfilled, and the kingdom of God is at hand. Repent, and believe in the gospel.”

We find that the message Jesus preached was “the gospel of the kingdom of God”, (which came from God the Father).  Note that Jesus also preached repentance and belief in the gospel.

As an aside, Mark 1:14 also tells us the “when”, which is after John the Baptist was put in prison.  This is also given by Luke 16:16.

Luk 16:16  “The law and the prophets were until John. Since that time the kingdom of God has been preached, and everyone is pressing into it.

Here are some other Scriptures which clearly state that the gospel Jesus preached was “the gospel of the kingdom of God”.

Mat 4:23  And Jesus went about all Galilee, teaching in their synagogues, preaching the gospel of the kingdom, and healing all kinds of sickness and all kinds of disease among the people.

Mat 9:35  Then Jesus went about all the cities and villages, teaching in their synagogues, preaching the gospel of the kingdom, and healing every sickness and every disease among the people.

Luk 4:43  but He said to them, “I must preach the kingdom of God to the other cities also, because for this purpose I have been sent.”

Luk 8:1  Now it came to pass, afterward, that He went through every city and village, preaching and bringing the glad tidings of the kingdom of God. And the twelve were with Him,

Jesus’s disciples also preached the kingdom of God.

Luk 9:1  Then He [Jesus] called His twelve disciples together and gave them power and authority over all demons, and to cure diseases.
Luk 9:2  He sent them to preach the kingdom of God and to heal the sick.

Act 8:12  But when they believed Philip as he preached the things concerning the kingdom of God and the name of Jesus Christ, both men and women were baptized.

The apostle Paul preached the kingdom of God.

Act 28:30  Then Paul dwelt two whole years in his own rented house, and received all who came to him,
Act 28:31  preaching the kingdom of God and teaching the things which concern the Lord Jesus Christ with all confidence, no one forbidding him.

The gospel of God and the gospel of Christ

The apostle Paul in his writings often used the term, “the gospel of God”, or “the gospel of Christ”.  Are these different to “the gospel of the kingdom of God”?  No, they are the same. 

The gospel of Jesus Christ is not the gospel about Christ, but rather the gospel He preached, which, as we have established, was the gospel of the kingdom of God.

The gospel of God is also the gospel of the kingdom of God, because the gospel Jesus preached was the message from the Father.  Jesus clearly stated that He spoke the words that the Father gave Him.

Joh 12:49  For I have not spoken on My own authority; but the Father who sent Me gave Me a command, what I should say and what I should speak.
Joh 12:50  And I know that His command is everlasting life. Therefore, whatever I speak, just as the Father has told Me, so I speak.”

Joh 14:24  He who does not love Me does not keep My words; and the word which you hear is not Mine but the Father’s who sent Me.

“The gospel of the kingdom of God”, “the gospel of God”, and “the gospel of Christ” are all different names for the same gospel which Jesus Christ delivered from the Father.

The kingdom of God

So we have established that Jesus preached the gospel of the kingdom of God, but what exactly is the kingdom of God?  The kingdom of God is the realm of beings that are God-like.  Jesus preached about entering into this kingdom by being born “again” to gain eternal life.

Jesus told the Pharisee named Nicodemus that he must be born again as a spirit being to enter the kingdom of God.

Joh 3:3  Jesus answered and said to him, “Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God.”
Joh 3:4  Nicodemus said to Him, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?”
Joh 3:5  Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.
Joh 3:6  That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.
Joh 3:7  Do not marvel that I said to you, ‘You must be born again.’

The apostle Paul wrote about this also, stating that we must be changed to spirit to inherit the kingdom of God.

1Co 15:50  Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; nor does corruption inherit incorruption.
1Co 15:51  Behold, I tell you a mystery: We shall not all sleep, but we shall all be changed—
1Co 15:52  in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised incorruptible, and we shall be changed.

For more information about this, see “What is the kingdom of God?” and “What does ‘Born Again’ mean?”

What did the apostles preach?

As mentioned earlier, the apostles preached the kingdom of God.  But they also preached about the name of Jesus Christ and the things which concern Him. 

Act 8:12  But when they believed Philip as he preached the things concerning the kingdom of God and the name of Jesus Christ, both men and women were baptized.

Act 28:30  Then Paul dwelt two whole years in his own rented house, and received all who came to him,
Act 28:31  preaching the kingdom of God and teaching the things which concern the Lord Jesus Christ with all confidence, no one forbidding him.

In the Gospels, Jesus did not go into any detailed explanation of His sacrifice for our sins.  However, His disciples did that in the epistles.  The apostles explained that Jesus Christ was the Son of God who died for our sins and rose again, that those who believe in Him might receive eternal life.  That is why, as we see in the references to Acts listed above, the apostles preached both the kingdom of God (what Jesus preached), as well as the name of Jesus Christ and things which concern Him (the full explanation of His sacrifice for our sins).

Conclusion

The true gospel is the good news about the kingdom of God and how we can enter into it to receive eternal life by being changed into spirit beings through repentance and acceptance of the sacrifice of Jesus Christ.