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So, you have Jesus, under the old covenant, dealing with the House of Israel .
This is not Paul's Gospel.
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I do believe it.
But now the way you misunderstand it.
You already admitted that Jesus couldn't have preached the Pauline Gospel because Jesus hadn't died yet.
At some point, your parenthetical Dispensation of Grace will end. But for those who are the lost sheep of the house of Israel, the Kingdom of Heaven is always at hand, because Jesus' words will never pass away. So when does Matthew 24:14 occur? since everything in context that happens before that verse has already happened, time after time.
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. 15 When ye therefore shall see the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place, (whoso readeth, let him understand: ) 16 Then let them which be in Judaea flee into the mountains:
Luke 21:24 And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.
Revelation 11:2 But the court which is without the temple leave out, and measure it not; for it is given unto the Gentiles: and the holy city shall they tread under foot forty two months. 3 And I will give [power] unto My two witnesses, and they shall prophesy a thousand two hundred threescore days, clothed in sackcloth. 4 These are the two olive trees, and the two candlesticks standing before the God of the earth.
The source of power to the two witnesses:
Revelation 7:3 Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads.
The two witnesses are churches:
Revelation 1:20 The mystery of the seven stars which thou sawest in My right hand, and the seven golden candlesticks. The seven stars are the angels of the seven churches: and the seven candlesticks which thou sawest are the seven churches.
IMO, Revelation 2:8 and Revelation 3:8