5 These twelve Jesus sent out and commanded them, saying:“Do not go into the way of the Gentiles, and do not enter a city of the Samaritans.
6 But go rather to the lost sheep of the house of Israel.
7 And as you go, preach, saying, ‘The kingdom of heaven is at hand.’
way of the Gentiles (v.5) — they were to avoid any contact with Gentiles
rather (v.6) = very, very much — exclusively
What does it mean? It meant that the promised Kingdom for Israel, and through Israel to the nations, the Kingdom will all its earthly blessings, was about to come. It was heralding the fact of the presence of the King to set up the Kingdom, if His own would have it. Such a preaching of the Kingdom of the heavens is not given now. After the church age closes by the removal of the church from the earth into heaven, as is foreshadowed by the vessel which Peter saw coming out of heaven and again received into heaven, then the kingdom will again draw nigh in the person of the returning King and Lord with His saints. — Gaebelein, pages 206-207
Israel was the nation with which God had entered into a covenant through Abraham, David and Jeremiah, and to which He had promised a Savior and Sovereign who would redeem and reign. The Old Testament anticipated blessings for Gentiles (Genesis 12:3; Isaiah 60:3; Amos 9:12). But blessings on Gentiles were to come through Israel’s Messiah. Such blessings could not come to them until Messiah ruled over His covenant people. At the time of the ministry of the Twelve, a message needed to go to Israel announcing to that nation that her King had arrived. Israel herself needed to come to faith before blessings could flow out from Israel to the nations of the earth.
Next we notice the message the Twelve were to preach: “The kingdom of heaven is near (Matthew 10:7). This was the message that Israel had first heard from John and the message that Christ had been publicly proclaiming. — Pentecost, page 193.
I copied pretty much everything Gaebelein and Pentecost had to say on these verses because all the other commentaries missed the mark by a huge margin, claiming that the Lord’s instructions to go to Israel only really just meant to go to Israel first and then, because Israel rejected it, to take the same message to the Gentiles. They all see the current church age in the latter verses of this chapter even though Paul says over and over again that that message was given to him exclusively.
The most important thing to realize about these verses is that, while it was Christ’s death and resurrection that saves us, His ministry on earth was not to us, for us or about us. It was to Israel in fulfillment of all the Old Testament promises to that nation. (And even the promises regarding the Gentiles in the Old Testament are (in the future) to be fulfilled through Israel. That’s why Paul says in Colossians 1:26 that: the mystery … has been hidden from ages and from generations, but now has been revealed to His saints.
Attempts to apply the Lord’s earthly ministry to us today, if not interpreted in this light, can only lead to confusion and contradiction.