They were NOT joined together IN BELIEF, but in UNBELIEF.
Rom 11:32 KJV For God hath concluded them all in unbelief, that he might have mercy upon all.
The promise is that God join them together in belief.
That is what the cross accomplished for believers of all nations, races, languages.
Act 2:4 And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance.
Act 2:5 And there were dwelling at Jerusalem Jews, devout men, out of every nation under heaven.
Act 2:6 Now when this was noised abroad, the multitude came together, and were confounded, because that every man heard them speak in his own language.
Act 2:7 And they were all amazed and marvelled, saying one to another, Behold, are not all these which speak Galilaeans?
Act 2:8 And how hear we every man in our own tongue, wherein we were born?
Act 2:9 Parthians, and Medes, and Elamites, and the dwellers in Mesopotamia, and in Judaea, and Cappadocia, in Pontus, and Asia,
Act 2:10 Phrygia, and Pamphylia, in Egypt, and in the parts of Libya about Cyrene, and strangers of Rome, Jews and proselytes,
Act 2:11 Cretes and Arabians, we do hear them speak in our tongues the wonderful works of God.
Act 2:12 And they were all amazed, and were in doubt, saying one to another, What meaneth this?
Act 2:13 Others mocking said, These men are full of new wine.
Act 2:14 But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judaea, and all ye that dwell at Jerusalem, be this known unto you, and hearken to my words:
Act 2:15 For these are not drunken, as ye suppose, seeing it is but the third hour of the day.
Act 2:16 But this is that which was spoken by the prophet Joel;
Act 2:17 And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams:
Act 2:18 And on my servants and on my handmaidens I will pour out in those days of my Spirit; and they shall prophesy:
Act 2:19 And I will shew wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapour of smoke:
Act 2:20 The sun shall be turned into darkness, and the moon into blood, before that great and notable day of the Lord come:
Act 2:21 And it shall come to pass, that
whosoever shall call on the name of the Lord shall be saved.
Rev 7:9 After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;
Rev 7:10 And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
Rev 7:11 And all the angels stood round about the throne, and about the elders and the four beasts, and fell before the throne on their faces, and worshipped God,
Rev 7:12 Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might, be unto our God for ever and ever. Amen.
Rev 7:13 And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they?
Rev 7:14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.
Rev 7:15 Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.
Rev 7:16 They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat.
Rev 7:17 For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and God shall wipe away all tears from their eyes.