Is the “Gospel” being preached today, the gospel Jesus and the Apostles preached?
Matthew 4:17 (NKJV)
Parable of the Mustard Seed
Mark 4:30–32; Luke 13:18, 19
31 Another parable He put forth to them, saying: “The kingdom of heaven is like a mustard seed, which a man took and sowed in his field, 32 which indeed is the least of all the seeds; but when it is grown it is greater than the herbs and becomes a tree, so that the birds of the air come and nest in its branches.”
Parable of the Leaven
33 Another parable He spoke to them: “The kingdom of heaven is like leaven, which a woman took and hid in three measures of meal till it was all leavened.”
Christ’s Kingdom is Not of This World
John 18:36–37 (NKJV)
36 Jesus answered, “My kingdom is not of this world. If My kingdom were of this world, My servants would fight, so that I should not be delivered to the Jews; but now My kingdom is not from here.”
37 Pilate therefore said to Him, “Are You a king then?”
Jesus answered, “You say rightly that I am a king. For this cause I was born, and for this cause I have come into the world, that I should bear witness to the truth. Everyone who is of the truth hears My voice.”
The New Testament is full of verses about the Kingdom. So is the Old Testament. They prophesied of this time when Christ would rule and His kingdom would come.
Old Testament Prophecies
Isaiah 9:6–7 (NKJV)
For unto us a Child is born, Unto us a Son is given; And the government will be upon His shoulder. And His name will be called Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace. Of the increase of His government and peace There will be no end, Upon the throne of David and over His kingdom, To order it and establish it with judgment and justice From that time forward, even forever. The zeal of the LORD of hosts will perform this.
Daniel 2:44 (NKJV)
44 And in the days of these kings the God of heaven will set up a kingdom which shall never be destroyed; and the kingdom shall not be left to other people; it shall break in pieces and consume all these kingdoms, and it shall stand forever.
Excellent Resources
The Kingdom That Turned the World Upsidedown by David Bercot is an excellent book on this subject. I highly recommend it!