Your teaching is gnostic. There is no NT allusion to the gospel being limited to the "lost" house of Israel. "All men everywhere" is who it applies to, and those who respond are grafted into the house of Israel as a "wild" vine is grafted into a cultivated vine. Rom 11:17.
My friend, read the scriptures Very carefully. Especially the one quoted by you Rom 11:17
17 And if some of the branches were broken off, and
you, being a wild olive tree, have been grafted in among them, and came to share the root and fatness of the olive tree,
Israel as an whole is represented by the Olive Tree.
The natural olive branches would be the Jews because Judea existed during the time of Messiah and the Apostles. That's the reason the reason the proselytes from many languages were coming to Jerusalem to keep the feasts of Israel.
On the other hand, the northern house of Israel didn't return from their Assyrian captivity (only a remnant were kept there by Assyrians). They were called Gentiles because they lived and mixed up with the heathens). However, Jews made them proselytes and established synagogues there as we can see Messiah visiting synagogues there in gospel accounts. There were many Samaritan proselytes.
The WILD OLIVE branches are being referred to them. Nevertheless, they are OLIVE branches separated long before the NT which became wild. Therefore, Paul uses the words very carefully and not as the Christendom which reads scriptures carelessly as having scales on their eyes.
No heathen nation has anything to do with the Olive Tree whether natural or wild.
Because of the unbelief of many Jews, they were cut off but some were grafted back (we can imagine person like Paul). In their place, the wild olive branches (the lost sheep of the house of Israel) were grafted.
Luke 2:
34 and Simeon blessed them, and said to Miriam, his mother, “
Behold, this child is set for the falling and the rising of many in Israel, and for a sign which is spoken against.
Regarding the Athenians - you got to see first Paul enterering a Synagogue there:
Acts 17:
16 Now while
Paul waited for them at Athens, his spirit was provoked within him as he saw the city full of idols.
17 So he reasoned in the synagogue with the Jews and the devout persons, and in the marketplace every day with those who met him.
If there was a Synagogue in Athens, Paul would forsee there would be more people in the city who would believe in the gospel. Market place is the best place to find them.
The preaching of Paul did bring fruits:
Acts 17:
34 But certain men joined with him and believed, among whom also was Dionysius the Areopagite, and a woman named Damaris, and others with them.
The scriptures give us the clue but we must go through them carefully. The gospel message is only for the two houses of Israel united as one with middle wall between them being demolished in Messiah under the New Covenant - Heb 8:8-11.
Moreover, I will leave you with this scripture:
Luk 19:
2 There was a man named
Zacchaeus. He was a chief tax collector, and he was rich.
9:
9 Yeshua said to him, “
Today, salvation has come to this house, because he also is a son of Abraham.