Why should I do not doubt but that he proved that both by reason, and also by testimonies of Scripture, which he taught concerning the resurrection and the heavenly life. But for good causes doth he call back those unto whom he speaketh unto the power of God, lest they judge thereof according to their own weak capacity. For nothing can more hardly sink into men's brains, than that men's bodies shall be restored when as they be once consumed. [1] Therefore, seeing it is a mystery far surpassing man's wit, let the faithful remember how far the infinite power of God doth reach, and not what they themselves comprehend; as the same Paul teacheth in the third chapter to the Philippians (Philippians 3:21). For when he hath said that our vile bodies shall be made like to the glorious body of Christ, he addeth immediately, "according to the mighty working whereby he is able to subdue all things to himself." But men are for the most part injurious [2] to God, who will not have his arm to reach any farther than their understanding and reason can reach; so that so much as in them lieth they would desire to restrain the greatness of his works (which surpasseth heaven and earth) unto their straits. [3] But, on the other side, Paul commandeth us to consider what God is able to do, that being lifted up above the world, we may learn to conceive the faith of the resurrection, not according to the weak capacity of our mind, but according to his omnipotency.

Footnotes

1 - "Ubi in nihilum redacta fuerint," after being reduced to nothing.

2 - "Maligni... et injurii," malignant and injurious,

3 - "Ad suas angustias," to their narrow capacity.

Why should it be thought - The force of this question will be better seen by an exclamation point after why τί ti. "What! is it to be thought a thing incredible?" etc. It intimates surprise that it should be thought incredible, or implies that no reason could be given why such a doctrine should be unworthy of belief.
A thing incredible - A doctrine which cannot be credited or believed. Why should it be regarded as absurd?
With you - This is in the plural number, and it is evident that Paul here addressed, not Agrippa alone, but those who sat with him. There is no evidence that Agrippa doubled that the dead could be raised, but Festus, and those who were with him, probably did, and Paul, in the ardor of his speech, turned and addressed the entire assembly. It is very evident that we have only an outline of this argument, and there is every reason to suppose that Paul would dwell on each part of the subject at greater length than is here recorded.
That God should raise the dead - Why should it be regarded as absurd that God - who has all power, who is the creator of all, who is the author of the human frame should again restore man to life and continue his future existence? The resurrection is no more incredible than the original creation of the body, and it is attended with no greater difficulties. And as the perfections of God will be illustrated by his raising up the dead; as the future state is necessary to the purposes of justice in vindicating the just and punishing the unjust, and as God is a righteous moral governor, it should not be regarded as an absurdity that he will raise up those who have died, and bring them to judgment.

That God should raise the dead? - As Agrippa believed in the true God, and knew that one of his attributes was omnipotence, he could not believe that the resurrection of the dead was an impossible thing; and to this belief of his the apostle appeals; and the more especially, because the Sadducees denied the doctrine of the resurrection, though they professed to believe in the same God. Two attributes of God stood pledged to produce this resurrection: his truth, on which his promise was founded; and his power, by which the thing could be easily affected, as that power is unlimited.
Some of the best critics think this verse should be read thus: What! should it be thought a thing incredible with you, if God should raise the dead?

(4) Why should it be thought a thing incredible with you, that God should raise the dead?
(4) He proves the resurrection of the dead, first by the power of God, then by the resurrection of Christ, of which he is a sufficient witness.

Why should it be thought a thing incredible with you,.... You Heathens and Sadducees; for the doctrine of the resurrection of the dead was thought an incredible doctrine by the Heathens in general, and therefore was laughed at by the Stoic and Epicurean philosophers at Athens, when preached by the apostle there; and by a particular sect among the Jews, the Sadducees; and the apostle may be thought either to address himself to Festus, the Roman governor, and to the chief captains, who were present, and, being Heathens, disbelieved this doctrine; or else to King Agrippa, who might be a Sadducee, and to such of the Sadducees as were in court, and expostulate with them, why it should be looked upon as a thing by no means to be credited,
that God should raise the dead; which may be understood both of the particular resurrection of Christ from the dead, which was not believed, neither by the Romans nor by the Jews, and neither by Pharisees nor Sadducees; or of the general resurrection of the dead, which was judged from the nature of things to be impracticable, and impossible by the latter, as well as by the Heathens: but since God is omniscient and omnipotent, and just and true, knows where every particle of a dead body lies, and can gather all together, and inspire with life; which he can as easily do, as to form all things out of nothing, as he did; and his justice and veracity seem to require, that the same bodies which have been partners with their souls in sinning, or in sufferings should share with them in woe or in happiness; it can neither be absurd, unreasonable, nor incredible, to suppose that God will raise them from the dead.

Why should it be thought a thing incredible . . . that God should raise the dead?--rather, "Why is it judged a thing incredible if God raises the dead?" the case being viewed as an accomplished fact. No one dared to call in question the overwhelming evidence of the resurrection of Jesus, which proclaimed Him to be the Christ, the Son of God; the only way of getting rid of it, therefore, was to pronounce it incredible. But why, asks the apostle, is it so judged? Leaving this pregnant question to find its answer in the breasts of his audience, he now passes to his personal history.

Is it judged by you an incredible thing - It was by Festus, Acts 25:19, to whom Paul answers as if he had heard him discourse.