I've never promoted that they were written before the cross, there is a reason for that.
Joh:14:16:
And I will pray the Father,
and he shall give you another Comforter,
that he may abide with you for ever;
Joh:14:26:
But the Comforter,
which is the Holy Ghost,
whom the Father will send in my name,
he shall teach you all things,
and bring all things to your remembrance,
whatsoever I have said unto you.
Can you put these references into a single thought?
The one from Luke was in a sermon Jesus gave just prior to the cross, the other one references the first verse below as being historical, meaning 70AD was in the past when it was written.
Lu:21:24:
And they shall fall by the edge of the sword,
and shall be led away captive into all nations:
and Jerusalem shall be trodden down of the Gentiles,
until the times of the Gentiles be fulfilled.
Jas:1:1:
James,
a servant of God and of the Lord Jesus Christ,
to the twelve tribes which are scattered abroad, greeting.