He that has received his testimony has set his seal to this that God is true.
All Commentaries on John 3:33 Go To John 3
John Chrysostom
AD 407
Here he touches his own disciples, as not being likely for a time to be firm believers. And that they did not even after this believe in Him, is clear from what is said afterwards; for John even when dwelling in prison sent them thence to Christ, that he might the more bind them to Him. Yet even then they scarcely believed, to which Christ alluded when He said, And blessed is he whosoever shall not be offended in Me. Matthew 11:6 And therefore now he said, And no man receives His testimony, to make sure his own disciples; all but saying, Do not, because for a time few shall believe in Him, therefore deem that His words are false; for, 'He speaks that He has seen.' Moreover he says this to touch also the insensibility of the Jews. A charge which the Evangelist at commencing brought against them, saying, He came unto His own, and His own received Him not. For this is no reproach against Him, but an accusation of those who received Him not. John 1:11
He that has received His testimony has set to his seal that God is true. Here he terrifies them also by showing that he who believes not on Him, disbelieves not Him alone, but the Father also; wherefore he adds: