This is an incorrect summary of the New Testament. Here's why...Jesus while preaching the good news (gospel) of the Kingdom of God/Heaven also said, during such dialogues, to His disciples thus:
Matthew 16:21
From that time forth began Jesus to shew unto his disciples, how that he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed , and be raised again the third day.
Matthew 17:9
And as they came down from the mountain, Jesus charged them, saying, Tell the vision to no man, until the Son of man be risen again from the dead .
Matthew 17:22-23
[17:22] And while they abode in Galilee, Jesus said unto them, The Son of man shall be betrayed into the hands of men: [17:23] And they shall kill him , and the third day he shall be raised again . And they were exceeding sorry.
Matthew 20:18-19
[20:18] Behold, we go up to Jerusalem; and the Son of man shall be betrayed unto the chief priests and unto the scribes, and they shall condemn him to death, [20:19] And shall deliver him to the Gentiles to mock, and to scourge, and to crucify him : and the third day he shall rise again .
Matthew 26:2
Ye know that after two days is the feast of the passover, and the Son of man is betrayed to be crucified.
Matthew 26:31-32
[26:31] Then saith Jesus unto them, All ye shall be offended because of me this night: for it is written, I will smite the shepherd , and the sheep of the flock shall be scattered abroad. [26:32] But after I am risen again , I will go before you into Galilee.
Mark 8:31
And he began to teach them, that the Son of man must suffer many things, and be rejected of the elders, and of the chief priests, and scribes, and be killed, and after three days rise again .
Mark 9:9
And as they came down from the mountain, he charged them that they should tell no man what things they had seen, till the Son of man were risen from the dead .
Mark 9:31
For he taught his disciples, and said unto them, The Son of man is delivered into the hands of men, and they shall kill him ; and after that he is killed, he shall rise the third day.
Mark 10:33-34
[10:33] Saying, Behold, we go up to Jerusalem; and the Son of man shall be delivered unto the chief priests, and unto the scribes; and they shall condemn him to death, and shall deliver him to the Gentiles: [10:34] And they shall mock him, and shall scourge him, and shall spit upon him, and shall kill him : and the third day he shall rise again .
Mark 12:7-8
[12:7] But those husbandmen said among themselves, This is the heir; come, let us kill him , and the inheritance shall be our's. [12:8] And they took him, and killed him, and cast him out of the vineyard.
Mark 14:8
She hath done what she could: she is come aforehand to anoint my body to the burying .
Mark 14:27-28
[14:27] And Jesus saith unto them, All ye shall be offended because of me this night: for it is written, I will smite the shepherd , and the sheep shall be scattered. [14:28] But after that I am risen, I will go before you into Galilee.
Mark 14:41
And he cometh the third time, and saith unto them, Sleep on now, and take your rest: it is enough, the hour is come; behold, the Son of man is betrayed into the hands of sinners.
Luke 9:22
Saying, The Son of man must suffer many things, and be rejected of the elders and chief priests and scribes, and be slain, and be raised the third day .
Luke 9:44
Let these sayings sink down into your ears: for the Son of man shall be delivered into the hands of men .
Luke 18:31-33
[18:31] Then he took unto him the twelve, and said unto them, Behold, we go up to Jerusalem, and all things that are written by the prophets concerning the Son of man shall be accomplished. [18:32] For he shall be delivered unto the Gentiles, and shall be mocked, and spitefully entreated, and spitted on: [18:33] And they shall scourge him, and put him to death : and the third day he shall rise again .
Luke 20:14-15
[20:13] Then said the lord of the vineyard, What shall I do? I will send my beloved son : it may be they will reverence him when they see him. [20:14] But when the husbandmen saw him, they reasoned among themselves, saying, This is the heir: come, let us kill him , that the inheritance may be ours. [20:15] So they cast him out of the vineyard, and killed him. What therefore shall the lord of the vineyard do unto them?
Luke 24:6-7
[24:6] He is not here, but is risen: remember how he spake unto you when he was yet in Galilee, [24:7] Saying, The Son of man must be delivered into the hands of sinful men, and be crucified, and the third day rise again .
John 3:14
And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up :
John 8:28
Then said Jesus unto them, When ye have lifted up the Son of man , then shall ye know that I am he, and that I do nothing of myself; but as my Father hath taught me, I speak these things.
John 10:17-18
[10:17] Therefore doth my Father love me, because I lay down my life , that I might take it again . [10:18] No man taketh it from me, but I lay it down of myself . I have power to lay it down, and I have power to take it again . This commandment have I received of my Father.
John 12:7,:23-24, 32-34
[12:7] Then said Jesus, Let her alone: against the day of my burying hath she kept this. [12:23] And Jesus answered them, saying, The hour is come, that the Son of man should be glorified. [12:24] Verily, verily, I say unto you, Except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit. [12:32] And I, if I be lifted up from the earth, will draw all men unto me.
Now compare the Gospel as the apostle Paul confirms in 1 Corinthians 15:
1 Corinthians 15: NKJV
15 Moreover, brethren, I declare to you the gospel which I preached to you, which also you received and in which you stand, 2 by which also you are saved, if you hold fast that word which I preached to you—unless you believed in vain.
3 For I delivered to you first of all that which I also received: that Christ died for our sins according to the Scriptures, 4 and that He was buried, and that He rose again the third day according to the Scriptures, 5 and that He was seen by Cephas, then by the twelve. 6 After that He was seen by over five hundred brethren at once, of whom the greater part remain to the present, but some have fallen asleep. 7 After that He was seen by James, then by all the apostles. 8 Then last of all He was seen by me also, as by one born out of due time.
9 For I am the least of the apostles, who am not worthy to be called an apostle, because I persecuted the church of God. 10 But by the grace of God I am what I am, and His grace toward me was not in vain; but I labored more abundantly than they all, yet not I, but the grace of God which was with me. 11 Therefore, whether it was I or they, so we preach and so you believed.
I know, there is a theory that the Gospel commanded by Christ in Luke 24:44-53 and confirmed by Paul in 1 Corinthians 15, is somehow in contention with the Gospel of the Kingdom of God/Heaven. They are not in contention with one another. We need one to achieve the other.
The Gospel of the Kingdom is one of Perfection. Capital "P" for this reason as Jesus points out in Matthew chapter 5:
Therefore you shall be perfect, just as your Father in heaven is perfect.(Matthew 5:48)
The Kingdom of God/Heaven is one of perfection. We puny hu-mans must be perfect as our Father in Heaven is Perfect. Who has been the only Person to walk this earth who is perfect. Jesus Christ. Who laid down His own life and rose from the dead so that we may be like Him at the Resurrection? Jesus Christ. Both Gospels are in harmony as the focal point is Christ Jesus who died for us and then rose from the dead with the Promised Hope of eternal life.
The apostles knew this well. As we see the apostle Paul continued to preach the Gospel of the Kingdom as he was preaching the Gospel of Grace as late as Acts 28:
Acts 28: NKJV
23 So when they had appointed him a day, many came to him at his lodging, to whom he explained and solemnly testified of the kingdom of God, persuading them concerning Jesus from both the Law of Moses and the Prophets, from morning till evening. 24 And some were persuaded by the things which were spoken, and some disbelieved.
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30 Then Paul dwelt two whole years in his own rented house, and received all who came to him, 31 preaching the kingdom of God and teaching the things which concern the Lord Jesus Christ with all confidence, no one forbidding him.
Paul was preaching the Kingdom of God and also Christ crucified and risen. Why?
Both are in harmony. The Kingdom is the perfection of God. Jesus became that perfection and those of us who are in Him will share the reward of eternal life.