John 2:23 Now when He was in Jerusalem at the Passover, during the feast, many believed in His name, observing His signs which He was doing. 24 But Jesus, on His part, was not entrusting Himself to them, for He knew all men, 25 and because He did not need anyone to testify concerning man, for He Himself knew what was in man.
In his brief time on earth, Jesus performed many works, both natural and miraculous, to establish his identity and authority. But while those signs proved his authenticated his words and established his divinity, they did not produce saving faith in the hearts of those who saw them.
23. Many believed. The Evangelist appropriately connects this narrative with the former. Christ had not given such a sign as the Jews demanded; and now, when he produced no good effect on them by many miracles—except that they entertained a cold faith, which was only the shadow of faith—this event sufficiently proves that they did not deserve that he should comply with their wishes. It was, indeed, some fruit of the signs, that many believed in Christ, and in his name, so as to profess that they wished to follow his doctrine; for name is here put for authority. This appearance of faith, which hitherto was fruitless, might ultimately be changed into true faith, and might be a useful preparation for celebrating the name of Christ among others; and yet what we have said is true, that they were far from having proper feelings, so as to profit by the works of God, as they ought to have done.
Yet this was not a pretended faith by which they wished to gain reputation among men; for they were convinced that Christ was some great Prophet, and perhaps they even ascribed to him the honor of being the Messiah, of whom there was at that time a strong and general expectation. But as they did not understand the peculiar office of the Messiah, their faith was absurd, because it was exclusively directed to the world and earthly things. It was also a cold belief, and unaccompanied by the true feelings of the heart. For hypocrites assent to the Gospel, not that they may devote themselves in obedience to Christ, nor that with sincere piety they may follow Christ when he calls them, but because they do not venture to reject entirely the truth which they have known, and especially when they can find no reason for opposing it. For as they do not voluntarily, or of their own accord, make war with God, so when they perceive that his doctrine is opposed to their flesh and to their perverse desires, they are immediately offended, or at least withdraw from the faith which they had already embraced.
When the Evangelist says, therefore, that those men believed, I do not understand that they counterfeited a faith which did not exist, but that they were in some way constrained to enroll themselves as the followers of Christ; and yet it appears that their faith was not true and genuine, because Christ excludes them from the number of those on whose sentiments reliance might be placed. Besides, that faith depended solely on miracles, and had no root in the Gospel, and therefore could not be steady or permanent. Miracles do indeed assist the children of God in arriving at the truth; but it does not amount to actual believing, when they admire the power of God so as merely to believe that it is true, but not to subject themselves wholly to it. And, therefore, when we speak generally about faith, let us know that there is a kind of faith which is perceived by the understanding only, and afterwards quickly disappears, because it is not fixed in the heart; and that is the faith which James calls dead; but true faith always depends on the Spirit of regeneration, (James ii. 17, 20, 26.) Observe, that all do not derive equal profit from the works of God; for some are led by them to God, and others are only driven by a blind impulse, so that, while they perceive indeed the power of God, still they do not cease to wander in their own imaginations.
24. But Christ did not rely on them. Those who explain the meaning to be, that Christ was on his guard against them, because he knew that they were not upright and faithful, do not appear to me to express sufficiently well the meaning of the Evangelist. Still less do I agree with what Augustine says about recent converts. The Evangelist rather means, in my opinion, that Christ did not reckon them to be genuine disciples, but despised them as volatile and unsteady. It is a passage which ought to be carefully observed, that not all who profess to be Christ’s followers are such in his estimation.
—John Calvin, Calvin’s Commentaries Volume XVII, Commentary on the Gospel according to John Volume I (Baker Books, 2009), 100–102.