An example, which was originally in Hebrew:
Psa 22:27 All the ends of the world shall remember and turn unto the LORD: and all the kindreds of the nations shall worship before thee.
This shows that it is 'the nations', not 'all nations'. We have to ask 'which nations' are being specified. That will give us the context. This is an important thing to point-out to people.
A red arrow is pointing next to the definite article, in Hebrew it looks very much the same in all cases, as far as I know. Sometimes a translation will omit the definite article.
It is in Genesis 22 too:
Gen 22:18 And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice.
I suppose the 'blessing' of the edomites and goats is that they go to hell. The Judgement of Nations is always a good verse to remember when someone asserts 'all nations' ...this is something Christ Himself said and He did not contradict Himself.
Compare Matthew 25, the Judgement of Nations, to the prophecy of the Old Testament:
Jer 30:11 For I am with thee, saith the LORD, to save thee: though I make a full end of all nations whither I have scattered thee, yet will I not make a full end of thee: but I will correct thee in measure, and will not leave thee altogether unpunished.
So then we can ask again 'which Nations'?. It cannot be 'all nations'. Christ was not in error.
The Greek definite Article is a little more complex than the Hebrew. But here is Bill's translation that initially sparked my realization.
The KJV
Mat 28:19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
The Christogenea New Testament
Mat 28:19 Therefore going you instruct all of the Nations, immersing them in the Name of the Father and the Son and the Holy Spirit,
So the KJV leaves-out the definite article to widen the context to the point where it apparently makes Christ into liar. Whereas the presence of the definite article narrows the context and thus we can begin to form a consistent context and interpretation that is in agreement with Messiah.
This one doesn't seem to have the definite article, but it certainly defines the context from the start:
Isa 66:20 And they shall bring all your brethren for an offering unto the LORD out of all nations upon horses, and in chariots, and in litters, and upon mules, and upon swift beasts, to my holy mountain Jerusalem, saith the LORD, as the children of Israel bring an offering in a clean vessel into the house of the LORD.
God is not the author of confusion.