"These twelve Jesus sent out after instructing them: Do not go in the way of the nations..." (Matthew 10:5)
“...I am sent only to the lost sheep of the house of Israel...” (Matthew 15:22)
During His ministry to Israel Jesus never went outside of the limits of the promised land. After Jesus had ascended back to His Father, Peter addressed men and women of Israel who had gathered in Jerusalem from all over the world to celebrate the Jewish feast of Pentecost.
"When the day of Pentecost had come...Peter stood up...and addressed the crowd...Fellow Jews and all of you who live in Jerusalem" ... "Men of Israel..." (Acts 2:1,14; 3:12).
Peter told them that their leaders had rejected their Messiah and had Him crucified, nevertheless, God had raised Him from the dead which made Jesus both Lord and Christ, and told them what they must do in order for Him TO RETURN to fulfill all unfulfilled promises made to Israel...
“Therefore, let all the house of Israel know for certain that God has made Him both Lord and Christ—this Jesus whom you crucified. Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, 'Brethren, what shall we do?' Peter said to them, 'Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins'...the things which God announced beforehand by the mouth of all the prophets, that His Christ would suffer, He has thus fulfilled. Therefore, repent and return, so that your sins may be wiped away, in order that times of refreshing may come from the presence of the Lord; and that He may send Jesus, the Christ appointed for you, whom heaven must receive until the period of restoration of all things about which God spoke by the mouth of His holy prophets from ancient time.'" (Acts 2:36-38; 3:18-21)
The other nations were at that time "excluded from the commonwealth of Israel" as Paul would later tell them...
"Therefore, remember that formerly you, the nations in the flesh, who are called Uncircumcision by the so-called Circumcision, which is performed in the flesh by human hands— remember that you were at that time separate from Christ, excluded from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world." (Ephesians 2:11-12)
The inclusion of the other nations in God's plan of salvation was a secret, a "mystery" hidden until revealed to the Apostle Paul after the death, entombment, resurrection, and ascension of Jesus. Paul was then told the secret...
"...you have heard of the stewardship of God’s grace which was given to me for you...which in other generations was not made known to the sons of men...to be specific, that THE NATIONS are fellow heirs and fellow members of the body, and fellow partakers of the promise in Christ Jesus through the good news, of which I was made a minister...to me, the very least of all saints, this grace was given, to preach to the nations the unfathomable riches of Christ, and to bring to light what is the administration of the MYSTERY which for ages has been hidden in God who created all things." (Ephesians 3:1-8).
It was the Apostle Paul, not the disciples of Jesus, who was chosen to take the good news of salvation to the other nations of the earth. And in Acts Chapter 13 Paul began doing so...
“For so the Lord has commanded us, I have placed you as a light for the nations, that you may bring salvation to the end of the earth. When the nations heard this, they began rejoicing and glorifying the word of the Lord." (Acts 13:46-49)
Thereafter, Paul preached about the saving grace of God to both the people of Israel and all of the other nations, but finally gave up on the Jews...
“Paul called together those who were the leading men of the Jews...they came to him at his lodging in large numbers; and he was explaining to them by solemnly testifying about the kingdom of God and trying to persuade them concerning Jesus, from both the Law of Moses and from the Prophets, from morning until evening...when they did not agree with one another, they began leaving after Paul had spoken one parting word...let it be known to you that this salvation of God has been sent to the nations; they will listen.” (Acts 28:17-28)
Most of the people of Israel have been hardened since that time, and only a small remnant of individuals believe Jesus is their Messiah today. But all the people of Israel are destined to believe when the "fulness of the nations" is complete.
"...a partial hardening has happened to Israel until the fullness of the nations has come in; and so ALL Israel will be saved; just as it is written, “the deliverer will come from Zion, He will remove ungodliness from Jacob. This is my covenant with them, when I take away their sins.” From the standpoint of the gospel they are enemies for your sake, but from the standpoint of God’s choice they are beloved for the sake of the fathers; for the gifts and the calling of God are irrevocable." (Romans 11:25)
Are people from other nations required to become Jewish? Of course not! We simply "rejoice" that God included all of us in his plan of salvation. This grace of God is for all nations, not just the people of Israel. The hope of ALL humanity is now in the return of Jesus.
"God was in Christ, reconciling the world to Himself, not counting their sins against them, and has given us this word of reconciliation...” (2 Corinthians 5:19)
“...the grace of God has appeared, bringing salvation to all humanity, instructing us to deny ungodliness and worldly desires and to live sensibly, righteously and godly in the present age, looking for the blessed hope and the appearing of the glory of our great God and Savior, Christ Jesus." (Titus 2:11-13)
Those of us who believe the gospel rejoice in our salvation and tell our families and friends that God loves them, He is not mad at them, and that they have been saved and reconciled to God through the death of His Son Jesus, a Jew born in Bethlehem who grew up and saved the world. He did so by dying for our sakes on the cross, shedding His blood to atone for the sins of the world. When we share this simple truth to friends and family we fulfill our commission - and that is GREAT!