They are held accountable for the blindness that caused God to harden them in that blindness.
It's time to reckon with:
Mk 4:11-12 - "The secret of the kingdom of God has been given to you. But to those on the outside everything is said in parables, so that
'they may be ever seeing but never perceiving,
and ever hearing but never understanding;
otherwise they might turn and be forgiven!' "
The decree has gone forth, the door is shut (Mt 25:10),
and Zion has already been judged.
For it is just that the unjust should glorify the justice of God.
In order words: one will face God for the blindness that caused Him to harden them in that blindness.
How about this: each person will be held accountable for their own actions.
One holds man accountable while the other will have God judging them because of something He did.
As speaking of the Jews, it would seem to be that God has offered to give them that heart of flesh through Christ:
Mar 1:4-5 John did baptize in the wilderness, and preach the baptism of repentance for the remission of sins. And there went out unto him all the land of Judaea, and they of Jerusalem, and were all baptized of him in the river of Jordan, confessing their sins.
Are you saying that the Jews are left to be unjust so that God's justice is glorified? Let us not forget:
God has not fully abandoned the Jews to be His instrument of justice. In Him dealing with them, He was patient and long suffering but it was their sins which drove Him away. But, as with any merciful God, if they confess their sin, He’ll forgive them just like He always has.
Is this not true:
Hos 5:15 I (God) will go and return to my place, till they acknowledge their offence, and seek my face: in their affliction they will seek me early.
And when will they repent and seek His face:
When the time comes that both Judah and Jerusalem is under seize (Zec 12:2) by those who wish to divide it (v3) that God:
Zec 12:10 And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and they shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn.
And what will God do when they have looked upon the One the have pierced:
Joe 3:21 For I will cleanse their blood that I have not cleansed: for the LORD dwelleth in Zion.
Which blood:
Mat 27:25 Then answered all the people, and said, His blood be on us, and on our children.
Certainly, God has not tossed away Zion:
Joe 3:16-17 The LORD also shall roar out of Zion, and utter his voice from Jerusalem; and the heavens and the earth shall shake: but the LORD will be the hope of his people, and the strength of the children of Israel. So shall ye know that I am the LORD your God dwelling in Zion, my holy mountain: then shall Jerusalem be holy, and there shall no strangers pass through her any more.