The First and Second Holy Temples were both destroyed on the 9th day of the Hebrew month of Menachem Av (three weeks from the 17th of Tammuz when the invaders breached the wall of Jerusalem, which this year is July 11, 20’17). The preceding three weeks are a period during which Jews mourn this loss, and fervently pray for the Third Temple that will be established by the Messiah from the dynasty of King David, speedily in our days. Recording time 2:43.
Gentiles were welcomed to bring their sacrificial offerings for G-d to the First and Second Temples in Jerusalem, and they will participate even more at the Third Temple – especially during the festival of Sukkot (Zechariah 14:16).
In his commentary on the Torah section beginning with Genesis 12:1, Ramban (Nachmanides) wrote:
“Even in the time of Joshua, … the Gentiles knew that this place was the most august of all, that it was at the center of the inhabited world; and [Torah] Tradition had taught them that it corresponds in this world to the celestial Temple where Divine Majesty, called (righteousness), resides.”
When the First Temple was inaugurated by King Solomon, he beseeched G-d with an eloquent prayer that included the following words (Kings I, 8:41-43) (which show that in the past, Gentiles were welcomed to the First and Second Temples, and that they will participate even more in the Third Temple):
“If a foreigner who is not of Your people Israel comes from a distant land for the sake of Your name – for they shall hear about Your great name and Your mighty hand and Your outstretched arm – when he comes to pray toward this House, oh, hear in Your heavenly abode and grant all [!] that the foreigner asks You for. Thus all the peoples of the earth will know Your name and revere You, as does Your people Israel; and they will recognize that Your name is attached to this House that I have built.”
Torah Law holds that Gentiles are allowed to bring burnt offerings to G-d in the Temple when it is standing in Jerusalem. There is a specific commandment to let us know that an animal (sheep, goat or bullock) offered in the Temple by a Gentile must be unblemished, to the same degree as the offering of a Jew. (Leviticus 22:25)
The Prophet Isaiah foretold us about the even greater participation of Gentiles that will take place at the Third Temple (Isaiah 2:2-3):
“And it will come to pass at the end of days that the mountain of G-d’s House will be firmly established, even higher than the peaks, and all the peoples will flow toward it as a river. And many nations will go and will cry, ‘Let us go up toward the mountain of G-d’s House, to the House of the L-rd of Jacob, and we will learn from His ways and walk in His paths, for out of Zion goes forth Torah and the word of G-d from Jerusalem.’ “
A Noahide is not required to fast on the 12th of Tammuz or the 9th of Av. Nevertheless Noahides may and should give charity during not only these 2 days but during the 3 weeks altogether in order to awaken Divine compassion.
You may help other Noahides here: http://worldnoahidecommunity.org/?page_id=8138