I am not sent but unto the lost sheep of the house of Israel." (Matthew 10:7)
Did God have different dispensations in dealing with man, as He even sent different apostles to different the two groups.
Joh 1:10 He was in the world, and the world was made by him, and
the world knew him not.
Joh 1:11 He (Jesus) came unto his own, and
his own received him not.
I have this excerpt pasted from a study of Matthew - Biography of the King that may be of help to you.
http://www.gracegod.com/Study Books/Matthew - Biography of the King.pdf
NOTE: The Grace and Glory Study books are in PDF format and can be read with the free
Adobe Reader
“There are twelve Kingdom apostles, as they have come to be known. This is a significant number; therefore it has lessons for us. It speaks of God as the Supreme One - "God all and in all." Those twelve chosen men are to rule over the restored Kingdom of Israel in the regeneration, when God's rule is manifested on the earth. Then later their names will be found in the foundations of the heavenly city, the emphatic expression of God's sovereignty in the whole universe. Those first chosen laborers are sent out two by two, in their preparatory testimony to Israel. Apparently their natural desire in this regard is considered. Simon or Peter, "a stone," and his brother Andrew, "the manly," a hint of the divine and human as the perfect witness, are called first. The sons of Zebedee, "the gifted of God," John and James, follow; afterwards Phillip, the lover of the race," with Bartholomew, supposed to be that Nathanael, "Given of God," whom Phillip brought to Jesus - John 1:45. Thomas, "twin," is joined to Matthew, "gift of Jehovah," tho' he styles himself "the taxgatherer." James the less, as he is called by men, tho' his name means "supplanter," being the Greek form of Jacob, goes out with Lebbaeus, "the Laver." Finally Simon, "hearkener," called the Canaanite, name of ill-favor, is linked with Judas Iscariot, name of illsavor. The meaning of the latter's name is most significant: Judas, "praise," Iscariot "the man of murder." That is he was called to praise the Lord; but instead he betrays Him and thus becomes His murderer even as the nation of whom he is the representative. They constitute the first workmen of the new order of things. They were chosen by the Master, the King and the Superintendent of His own interests. He carefully instructs them as to their respective fields of labor, their duties and their conduct while on their journey in His service. He does not leave anything to their choice or expediency. The plan of operations, while simple, is all mapped out by Himself. The directions are ample; they cover every phase of their ministry. Their sphere of service is limited to the "lost sheep" of the house of Israel. Note that they are sheep, tho' wandering away from the fold. They are absolutely forbidden to go to the Samaritans or the Gentiles. Remember, they are Kingdom apostles, and as such are sent to this highly favored nation. They were to proclaim the near-coming of His Kingdom and their preaching was to be accompanied with mighty manifestations as signs to the people. The Master assures them that sickness and death would yield to their command. Leprosy would be cleansed and all the power of Satan would be defeated. He Himself had just demonstrated the above victory; therefore He is sending them out in the very same power which was His enabling.”
Rom 3:22 Even the righteousness of God
which is by faith of Jesus Christ unto all and upon all them that believe: for
there is no difference:
Rom 3:23 For all have sinned, and come short of the glory of God
Rom 9:24 Even us, whom
he hath called, not of the Jews only, but also of the Gentiles?
Rom 11:13 For I speak to you Gentiles, inasmuch as I (Paul) am the apostle of the Gentiles,
Gal 2:7 But contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as
the gospel of the circumcision
was unto Peter;
Gal 2:8 (For he that wrought effectually in Peter to the apostleship of the circumcision, the same was mighty in me toward the Gentiles
Did this mean actual Jews? Or are we Gentiles , thinking of John 3:16, able to be grafted in to the house of Israel? 
This is very concerning at the moment.
