How then shall the scriptures be fulfilled, that so it must be done?

how then may the Writings be fulfilled, that thus it behoveth to happen?'

But how then would the Writings come true, which say that so it has to be?

But in that case how would the scriptures be fulfilled, which say that this must be?"

How then shall the Scriptures be fulfilled? By this expression Christ means, that he ought not to attempt any method of escaping death, to which he knew that he was called by the Father. For himself, indeed, he had no need of the Scriptures to inform him that God had appointed that he should die at that time; but because mortals do not know what God has determined to do until it be revealed by his word, Christ, with a view to his disciples, properly refers to the testimony which God gave of his will. We know that whatever affliction happens to us, it is inflicted by God himself; but since we are uncertain as to the result, when we seek remedies which he allows, we do not rise against his government; but when his will has been ascertained, nothing more remains for us than to acquiesce. Though in this passage Christ teaches nothing more than that he ought patiently to suffer death, because the Scriptures have declared that it must be so, yet the use of this doctrine is evidently more extensive, namely, that Scripture is a sufficient bridle for subduing the rebellion of the flesh; because God points out to us what is his. will for the very purpose of keeping us in subjection to his will. Accordingly, Paul ascribes to Scripture this office, that it trains us to patience, (Romans 15:4,) and supplies us with all the comfort that we need in adversity. His reproof of the disciples, as given by Luke, is more brief, Permit them to do thus far; but still he severely condemns their presumption, in having gone so far as to perform an unlawful action, though at the same time he holds out a hope of pardon, if they suppress their improper zeal, and proceed no farther.

But how then shall the scriptures be fulfilled - That is, the Scriptures which foretold of his dying for the world.
In some way that must be accomplished, and the time had come when, having finished the work which the Father gave him to do, it was proper that he should submit to death. This was said, doubtless, to comfort his disciples; to show them that his death was not a matter of surprise or disappointment to him; and that they, therefore, should not be offended and forsake him.

But how then - Had I such a defense - shall the Scriptures be fulfilled, which say, that thus it must be? That is, that I am to suffer and die for the sin of the world. Probably the Scriptures to which our Lord principally refers are Psalm 22, 69, and especially Isaiah 53:1-12, and Daniel 9:24-27. Christ shows that they had no power against him but what he permitted; and that he willingly gave up himself into their hands.

(z) But how then shall the scriptures be fulfilled, that thus it must be?
(z) By this questioning he answers a sly objection, for they might have asked him why he did not in this his great extremity of danger call to his Father for aid: but to this objection he answers by this question.

But how then shall the Scriptures be fulfilled,.... That is, should Christ make such a request to his Father, and he should grant it, and an host of angels should be sent to rescue him, and he should be rescued by them; how then should the Scriptures, which speak of Christ's being taken, and led as a lamb to the slaughter, and of his various sufferings, and the circumstances of them, have their accomplishment? "declaring", as the Arabic version supplies, or as the Ethiopic version, "which say",
that thus it must be; that the Messiah must be apprehended, and suffer, and die. The several parts of the sufferings of the Messiah are foretold in the writings of the Old Testament; the spirit of Christ, in the prophets, testified before hand of them; as that he should be reproached and despised of men, Psalm 22:6, be spit upon, smote, and buffeted, Isaiah 1:5, be put to death, Psalm 22:15, and that the death of the cross,
Psalm 22:15, and be buried, Isaiah 53:9, and also the several circumstances of his sufferings, which led on to them, or attended them; as the selling him for thirty pieces of silver,
Zac 11:12, the betraying him by one of his familiar friends,
Psalm 41:9, the seizing and apprehending him, and which is particularly referred to here, Isaiah 53:7, his disciples forsaking him, Zac 13:7, and even his God and Father, Psalm 22:1, his suffering between two thieves, Isaiah 53:12, the parting of his garments, and casting lots on his vesture, Psalm 22:18, the giving him gall and vinegar when on the cross, Psalm 69:21, and not breaking any of his bones, Psalm 34:20, yea, the Scriptures not only declared, that these things should be; but the necessity of them also, that they must be; because of the purposes and decrees of God, which are eternal, immutable, and unfrustrable; for as God had determined on his salvation of his people by Christ, and that through his sufferings and death, these were determined by him also, even the time, nature, manner, and circumstances of them; and which the Scriptures declare, and therefore must be likewise; and because of the covenant of grace, which is sure, unalterable, and unchangeable; in which Christ agreed to assume human nature, to obey, suffer, and die in it, and so do his Father's will, which was to bear the penalty of the law, and undergo the sufferings of death, and which therefore must be, or Christ's faithfulness fail. Moreover, on account of the law and justice of God, which required his bearing the curse, as well as fulfilling the precept of the law: and especially on account of the salvation of his people, which could not be effected without them, they must be. Christ, in these words, discovers a very great concern for the fulfilling of Scripture; and that because it is the word of God, which must not be broken; and because throughout it he is spoken of, in the volume of it, it is written of him, to do the will of God; even in the law of Moses, and in the Prophets, and in the Psalm: and besides, he was the minister of the circumcision, to confirm the promises made unto the fathers; and even agreeably to them, and upon the foundation of them, he had himself predicted his own sufferings: and as those were to be the rule of the faith and practice of his people in all ages, he was concerned for their accomplishment in every point; and which may teach us to value the Scriptures, and to be confident of the fulfilment of them in things yet future.