Isaiah 56

"For thus says the Lord:
“To the eunuchs who keep My Sabbaths,
And choose what pleases Me,
And hold fast My covenant,
5 Even to them I will give in My house
And within My walls a place and a name...

The Lord God, who gathers the outcasts of Israel, says,
“Yet I will gather to him
Others besides those who are gathered to him.” vv.4-5,8

Read chapter 56

Gentiles, or nations, are told of the promise that they will get to be in the Kingdom too!  This wasn't a new thing or secret that wasn't revealed until the New Testament time period, but something the Israelites were aware of because of the prophesies of God's word concerning the future and other nations other than Israel.  The Jews during the time of the Acts period and after just weren't happy about it starting to take place during their time and what it actually meant and looked like of the gospel of Jesus Christ being for all men and becoming coheirs of the blessings (Ephesians 3:6) and treated equal now by God.  During this time of Isaiah there were already some gentiles that became part of Israel as either a eunuch or proselyte who were those that feared the God of Israel and chose to follow Him. They were faithful servants and chose what pleased God (v.4), desiring to keep God's commandments.  This also shows that everyone who believes doesn't just become an Israelite, but that there will be many nations gathered together in the future.

How would you respond if you were an Israelite and found out that you were to share your blessing to other people that were looked at as "less than"?  Do you think you would have been a eunuch or proselyte during the Old Testament time?