The gospel Preached to the Whole World?

"And this gospel of the kingdom will be preached in the whole world as a testimony to all nations, and then the end will come."
-Matthew 24:14

This one verse, taken out of context by well-meaning Christians, is used to explain why Jesus has not yet returned. But is it actually true? Did Jesus ever state that every single isolated tribe on planet Earth had to hear the Gospel before He returned? 

This is part of one of the biggest misunderstandings of the bible. People fail to see that this was all about Israel. The entire Old Testament promised a coming redeemer or Messiah, who would present Himself to Israel and bring salvation from sin. This salvation would then go out to the world. 

The Old Covenant was not God's permanent intention for mankind. It was a school master, a guardian, that revealed our desperate need for a saviour and also contained the shadows and signposts that pointed forward to that Saviour. This promised Messiah finally came, and the people to whom He came, rejected and crucified Him. Before His Passion, Jesus promised He would return to the same generation who rejected Him in Judgement. He tied this return to the destruction of the Temple, the desolation of Jerusalem and Judea, and the fiery destruction of punishment of national old covenant Israel. 

The Gospel was the fulfilment of the Law. Jesus fulfilled the Law. It was always about Him. Man is by nature dead in sin and incapable of living a righteous life. Righteousness is only found in the person of Jesus Christ. The Gospel is about the perfect sacrifice for sin. The Lamb of God. All who believe that Jesus died for sin and rose from the dead and trust in Him as their saviour, are saved. There is no other requirement for salvation. This was always God's intention for redeeming mankind. But as Paul writes and as Jesus repeatedly stated, He came to the Jews first. His business was with them. So before He returned to Judea in Judgement, the Gospel had to go out into the world first. But this was not the entire physical world. It was the Jewish world. Jews were scattered all over the Roman Empire, around the Mediterranean. The Roman Empire was the centre of the world at this time in history, and conditions were primed for the Gospel to be established outside of Israel, and then spread to the rest of the world proper. 

As Jesus promised, the Gospel was preached to the whole Jewish-Roman world, during the last days and before the end of the age. 

Christians sadly do not register in their conscious minds when they read certain scriptures. Scripture records the fulfilment of this prophecy of the Gospel going out to the whole world. Here are a few:

the faith and love that spring from the hope stored up for you in heaven and about which you have already heard in the true message of the gospel 6 that has come to you. In the same way, the gospel is bearing fruit and growing throughout the whole world—just as it has been doing among you since the day you heard it and truly understood God’s grace.
-Colossians 1:5-6

 if you continue in your faith, established and firm, and do not move from the hope held out in the gospel. This is the gospel that you heard and that has been proclaimed to every creature under heaven, and of which I, Paul, have become a servant.
-Colossians 1:23

Consequently, faith comes from hearing the message, and the message is heard through the word about Christ. 18 But I ask: Did they not hear? Of course they did:

“Their voice has gone out into all the earth,
    their words to the ends of the world.”
-Romans 10:17-18

The battle cry of the Reformation was Sola Scriptura. When you read the scripture and actually pay attention, you can see it clears up these misunderstandings and interprets itself without the need for confusion.