Judaism expects the Kingdom of God to be brought in by the Messiah:
What Will the Mashiach Do?
Before the time of the mashiach, there shall be war and suffering (Ezekiel 38:16)
The mashiach will bring about the political and spiritual redemption of the Jewish people by bringing us back to Israel and restoring Jerusalem (Isaiah 11:11-12; Jeremiah 23:8; 30:3; Hosea 3:4-5). He will establish a government in Israel that will be the center of all world government, both for Jews and gentiles (Isaiah 2:2-4; 11:10; 42:1). He will rebuild the Temple and re-establish its worship (Jeremiah 33:18). He will restore the religious court system of Israel and establish Jewish law as the law of the land (Jeremiah 33:15).
Olam Ha-Ba: The Messianic Age
The world after the messiah comes is often referred to in Jewish literature as Olam Ha-Ba (oh-LAHM hah-BAH), the World to Come. This term can cause some confusion, because it is also used to refer to a spiritual afterlife. In English, we commonly use the term "messianic age" to refer specifically to the time of the messiah.
Olam Ha-Ba will be characterized by the peaceful co-existence of all people (Isaiah 2:4). Hatred, intolerance and war will cease to exist. Some authorities suggest that the laws of nature will change, so that predatory beasts will no longer seek prey and agriculture will bring forth supernatural abundance (Isaiah 11:6-11:9). Others, however, say that these statements are merely an allegory for peace and prosperity.
All of the Jewish people will return from their exile among the nations to their home in Israel (Isaiah 11:11-12; Jeremiah 23:8; 30:3; Hosea 3:4-5). The law of the Jubilee will be reinstated.
In the Olam Ha-Ba, the whole world will recognize the Jewish G-d as the only true G-d, and the Jewish religion as the only true religion (Isaiah 2:3; 11:10; Micah 4:2-3; Zechariah 14:9). There will be no murder, robbery, competition or jealousy. There will be no sin (Zephaniah 3:13). Sacrifices will continue to be brought in the Temple, but these will be limited to thanksgiving offerings, because there will be no further need for expiatory offerings.
So the speaker in Luke 14:15 was being skeptical about Jesus’s claims to be the Messiah, in the absence of these signs. But Jesus taught a different view of what the Kingdom of God would be. The victory was not over political foes, but spiritual ones:
John 3:3Jesus answered and said to him, “Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.”
When Jesus tells Nicodemus that unless a person needed to be born again, they would not enter the kingdom of God, He was talking about a situation where a person would have access to union with God, so that even the demons submitted to them, apart from the ability to do other things that showed God's involvement, His finger. He and Nicodemus were talking about the same thing, only He called it the Kingdom of God:
John 3:1Now there was a man of the Pharisees, named Nicodemus, a ruler of the Jews; 2this man came to Jesus by night and said to Him, “Rabbi, we know that You have come from God as a teacher; for no one can do these signs that You do unless God is with him.”
Luke 11:20"But if I cast out demons by the finger of God, then the kingdom of God has come upon you.
All Scripture from the NASB.