2 Samuel 7:23-24(NIV)
And who is like your people Israel _ the one nation on earth that God went out to redeem as a people for himself, and to make a name for himself, and to perform great and awesome wonders by driving out nations and their gods from before your people, whom you redeemed from Egypt?
You have established your people Israel as your very own forever, and you, O LORD, have become their God.

There is a people on the earth found in every nation under the sun who are destined to be one nation under God!

Exodus 19:5-6(NIV)
Now if you obey me fully and keep my covenant, then out of all nations you will be my treasured possession. Although the whole earth is mine,
you will be for me a kingdom of priests and a holy nation.' These are the words you are to speak to the Israelites."

This nation is not made up of people who have been able to keep God's law and be qualified to be His own based on their own merit.
It is made up of people who could never qualified on their own merit but humbly and willingly accepted God's loving offer of grace through the sacrifice of His only Son,the Lord Jesus Christ so as to become born anew of Him (John 1:12-13) into this nation.
For Christ has fully obeyed God and kept His 'old' covenant to redeem sinful mankind so as to make a 'new' and better covenant between God and mankind.

1 Peter 2:9(NIV)
But you are a chosen people, a royal priesthood, a holy nation, a people belonging to God, that you may declare the praises of him who called you out of darkness into his wonderful light.

As each one of these chosen people relates to the others based on who they all are in the Spirit-one nation under God,that oneness is manifested to the world!
A member of 'one nation' has to show God's unconditional love towards others just as God has shown that same kind of love towards oneself (Eph.5:1-2) even if that other person does not look 'lovable' or one does not feel love towards that person!

Ephesians 4:1-6(NIV)
As a prisoner for the Lord, then, I urge you to live a life worthy of the calling you have received.
Be completely humble and gentle; be patient, bearing with one another in love.
Make every effort to keep the unity of the Spirit through the bond of peace.
There is one body and one Spirit-just as you were called to one hope when you were called-
one Lord, one faith, one baptism;
one God and Father of all, who is over all and through all and in all.

Since one's natural mind has been formerly programmed to 'love' and 'hate' certain kinds of people it needs to be renewed (Rom.12:2;Eph.4:23) continually with this revelation!
One begins to regard other members of this 'one nation' more precious than one's personal likes and dislikes!
For the light of this spiritual reality is more powerful than the darkness of these people's apparent disunity in the physical realm!!!

John 1:5(AMP)
And the Light shines on in the darkness, for the darkness has never overpowered it [put it out or absorbed it or appropriated it, and is unreceptive to it].

Unbelief in this divine revelation makes a member of 'one nation' to just try to be one with other members, when one is already one with them in the realm of the Spirit!
Such attempts however noble only work against the corporate destiny of God's people!
But as the members of this 'one nation' catch,keep and live out this spiritual reality,it is progressively demonstrated to amaze the world and give glory to God (Psalm 133)!
With men,this oneness is impossible but with God,and those that believe...it is possible!!! (Mark 10:27,9:23)

Psalm 33:12(NIV)
Blessed is the nation whose God is the LORD,
the people he chose for his inheritance.

Bible quotations above are from the New International Version (NIV) and the Amplified Bible(AMP)