If the church be among the gathered nations, why would they not instead be identified by the Spirit being God's children? Do you see this gathering as fulfilling the "rapture" of the church in 1 Thessalonians 4? These are identified as being "in Christ", so wouldn't that be the distinction?
This is how I see it. We know that the parable of the sheep and the goats belongs not to this Age, but to the coming Age of Messiah's reign, because the introduction declares this, saying,
"When the Son of man shall come in his glory and all the holy angels with him, then shall he sit upon the Throne of his glory, and before him shall be gathered all nations; and he shall separate them one from another as a shepherd divideth his sheep from the goats." Those sheep and goats will not include the Church, to whom the promise is,
"When he shall appear, we also shall appear with him in glory" – sharing his Throne. (1 John 3:2)
The salvation of the Church will be finished before the salvation of the world will begin. Matthew 25:31-46 pictures the salvation of the world, showing us how every member of Adam's race will be on trial during the reign of Messiah and, by his obedience or disobedience to the light and knowledge then prevailing, he will be deciding his own everlasting future, either as a sheep or as a goat. It will require the entire one thousand years of Messiah's reign to complete the testing and separating work.
All then obedient will be recognized as children of God and brethren. All the disobedient will be reckoned as children of the Adversary and worthy to share his fate, because, under favorable conditions, they were rebellious. Such shall be destroyed with Satan in the Second Death, which is symbolically represented as fire, because fire is always destructive, never preservative. On the contrary, the sheep class at the conclusion of Messiah's reign will have reached perfection, the image and likeness of God, on the human plane. These will be invited to become the kings of earth under the Divine supervision – even as was Adam in his original perfection – crowned with glory and honor and set over the earthly creation. – Psalm 8:3-5.
The terms and conditions which will test and determine who will be sheep and who will be goats, who will be obedient or disobedient to the Divine regulations, will be mercy, kindness, love. The loving and sympathetic character is the only one which God purposes shall have eternal life, either on the heavenly or on the earthly plane – all having either the wolfish or devilish character, or even the goat character – of waywardness and unsubmissiveness, will be accounted unworthy of any further blessing after the close of the reign of Messiah. The testing then will not be as to believing or disbelieving, striving to do well or not striving to do well. The Church is dealt with now along such lines. God's dealings with us make allowances for our unwilling imperfections. But in the trial of the world in the future every man shall be tried according to his work, not according to his faith. In that time knowledge will have practically supplanted faith; hence faith will have no special rewards. Works will then have the rewards, and each member of the race will be expected to strive for perfect works and to be assistants of the Great King Emmanuel and his Bride, the Church on the spirit plane. Mankind will be enabled gradually to attain such perfection of mind and of body as will make perfect works possible. At the conclusion of the Millennial Age perfect works only will be rewarded.
The rewards that will be granted to the "sheep" class at the close of Messiah's Kingdom will be life eternal and possessors of the earthly Kingdom originally given to Adam, but lost through disobedience, and redeemed by the sacrifice of Jesus and restored by his Messianic reign, for which we pray,
"Thy Kingdom come; thy will be done on earth as in heaven." Matthew 6:10
As for the "goat" class, their punishment will consist of destruction in fire, or destruction everlasting, the Second Death – the destruction which God has already determined for Satan and all who are his messengers and servants, after the manner of this goat class – because, with all the favorable opportunities, they failed to develop such characters as God could reward with life everlasting. The contrast is emphasized in verse 46. These (the goat class) shall go away into eternal punishment; but the righteous, the sheep class, into eternal life. The contrast is perfect. The one gets life to all eternity. The other gets the specified punishment of destruction to all eternity. The Greek word here translated punishment is
kolasin, which signifies restraint, cutting off – in this case cutting off from life – Second Death.
"The wages (punishment) of sin is death." - Romans 6:23
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