A Christian wife is encouraged to stay with a heathen husband because her faith is something that umbrellas the whole family. A sinner in the family would probably be the one that is forgiven 70 x 7 rather than any stranger with a story about belonging to the same congregation. That is the family for a Christian be it a man, woman and child where faith is in the same Gospel as Paul taught in that Gentiles became a 'child of a Jewish teacher' as far as salvation was concerned.
Neither Greek nor Jew would certainly apply to the personal qualities of having a relationship with God with the addition that the rules for the new earth would apply to when a person can be judged on matters of sin. That would mean you would find no Gentile under 20 that is in sin that requires repenting to have it lifted. The list of things that is given that required repenting doesn't seem to be any different than the ones given to the Gentiles that read the first edition of Revelation.
1Pe:4:6-19:
For for this cause was the gospel preached also to them that are dead,
that they might be judged according to men in the flesh,
but live according to God in the spirit.
But the end of all things is at hand:
be ye therefore sober,
and watch unto prayer.
And above all things have fervent charity among yourselves:
for charity shall cover the multitude of sins.
Use hospitality one to another without grudging.
As every man hath received the gift,
even so minister the same one to another,
as good stewards of the manifold grace of God.
If any man speak,
let him speak as the oracles of God;
if any man minister,
let him do it as of the ability which God giveth:
that God in all things may be glorified through Jesus Christ,
to whom be praise and dominion for ever and ever.
Amen.
Beloved,
think it not strange concerning the fiery trial which is to try you,
as though some strange thing happened unto you:
But rejoice,
inasmuch as ye are partakers of Christ's sufferings;
that,
when his glory shall be revealed,
ye may be glad also with exceeding joy.
If ye be reproached for the name of Christ,
happy are ye;
for the spirit of glory and of God resteth upon you:
on their part he is evil spoken of,
but on your part he is glorified.
But let none of you suffer as a murderer,
or as a thief,
or as an evildoer,
or as a busybody in other men's matters.
Yet if any man suffer as a Christian,
let him not be ashamed;
but let him glorify God on this behalf.
For the time is come that judgment must begin at the house of God:
and if it first begin at us,
what shall the end be of them that obey not the gospel of God?
And if the righteous scarcely be saved,
where shall the ungodly and the sinner appear?
Wherefore let them that suffer according to the will of God commit the keeping of their souls to him in well doing,
as unto a faithful Creator.
Re:9:20-21:
And the rest of the men which were not killed by these plagues yet repented not of the works of their hands,
that
they should not worship devils,
and idols of gold,
and silver,
and brass,
and stone,
and of wood:
which neither can see,
nor hear,
nor walk:
Neither repented they of t
heir murders,
nor of their sorceries,
nor of their fornication,
nor of their thefts.
Phill Collins - Another day in paradise - YouTube