The "Gospel of the Kingdom", as you put it, is an obscure 19th century doctrine known as
Ultradispensationalism and therefore most Christians have no idea what you're talking about.
Obscure 19th century doctrine??
Matthew 23:13 But woe unto you, scribes and Pharisees, hypocrites! for ye shut up the kingdom of heaven against men: for ye neither go in yourselves, neither suffer ye them that are entering to go in.
Matthew 24: 11 And many false prophets shall rise, and shall deceive many. 12 And because iniquity shall abound, the love of many shall wax cold. 13 But he that shall endure unto the end, the same shall be saved. 14 And this GOSPEL OF THE KINGDOM shall be preached in all the world for a witness unto all nations; and then shall the end come.
Luke 16: 15 And he said unto them, Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God. 16 The law and the prophets were until John: since that time the kingdom of God is preached, and every man presseth into it.
Mark 16: 15 And he said unto them, Go ye into all the world, and preach the gospel to every creature.
Which gospel? }}}}
Luke 4: 43 And he said unto them, I must preach the kingdom of God to other cities also: for therefore am I sent.
Mark 1: 14 Now after that John was put in prison, Jesus came into Galilee, preaching the gospel of the kingdom of God, 15 And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.
Matthew 4: 23 And Jesus went about all Galilee, teaching in their synagogues, and preaching the gospel of the kingdom...
Matthew 24: 14 And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come.
Matthew 9: 35 And Jesus went about all the cities and villages, teaching in their synagogues, and preaching the gospel of the kingdom
Luke 8: 1 And it came to pass afterward, that he went throughout every city and village, preaching and shewing the glad tidings of the kingdom of God: and the twelve were with him,
Luke 9: 1 Then he called his twelve disciples together, and gave them power and authority over all devils, and to cure diseases. 2 And he sent them to preach the kingdom of God, and to heal the sick.
Mark 4:11 And he said unto them, Unto you it is given to know the mystery of the kingdom of God: but unto them that are without, all these things are done in parables
Acts 28: 23 And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening.
Matthew 13:19 When any one heareth the word of the kingdom, and understandeth it not, then cometh the wicked one, and catcheth away that which was sown in his heart. This is he which received seed by the way side.
Luke 8:10 And he said, Unto you it is given to know the mysteries of the kingdom of God: but to others in parables; that seeing they might not see, and hearing they might not understand.
John 18:36 Jesus answered, My kingdom is not of this world: if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews: but now is my kingdom not from hence.
Matthew 19: 23 Then said Jesus unto his disciples, Verily I say unto you, That a rich man shall hardly enter into the kingdom of heaven.
Matthew 13:44 Again, the kingdom of heaven is like unto treasure hid in a field; the which when a man hath found, he hideth, and for joy thereof goeth and selleth all that he hath, and buyeth that field.
Mark 10:15 Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child, he shall not enter therein.
Luke 9: 10 And the apostles, when they were returned, told him all that they had done. And he took them, and went aside privately into a desert place belonging to the city called Bethsaida. 11 And the people, when they knew it, followed him: and he received them, and spake unto them of the kingdom of God, and healed them that had need of healing.
Colossians 1:13 Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son
Matthew 19:24 And again I say unto you, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God.
1 Corinthians 15:50 Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption.
Romans 14:17 For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.
Matthew 13:33 Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened.
Mark 1:15 And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.
Matthew 19:14 But Jesus said, Suffer little children, and forbid them not, to come unto me: for of such is the kingdom of heaven.
Matthew 3:2 And saying, Repent ye: for the kingdom of heaven is at hand.
Matthew 13:52 Then said he unto them, Therefore every scribe which is instructed unto the kingdom of heaven is like unto a man that is an householder, which bringeth forth out of his treasure things new and old.
Luke 17:21 Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you.
Matthew 25:34 Then shall the King say unto them on his right hand, Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
Luke 16:16 The law and the prophets were until John: since that time the kingdom of God is preached, and every man presseth into it.
Mark 10:24 And the disciples were astonished at his words. But Jesus answereth again, and saith unto them, Children, how hard is it for them that trust in riches to enter into the kingdom of God!