John 4:29

All things that ever I did - The Jews believed that one essential characteristic of the Messiah would be, that he should be able to tell the secrets of all hearts. This they believed was predicted, Isaiah 11:2, Isaiah 11:3.

When the famous impostor Barchochab, who rose up under the empire of Adrian, about a hundred years after the incarnation, professed himself to be the Messiah, after having been deceived by him for two years, they at last thought of putting his divinity to proof on this ground: they brought before him persons whom he did not know, some of whom were very vicious, and others of a different character; they desired him to point out who were the righteous, and who were the wicked; which when he could not do, they rose up and put him to death. La Bible de Martin.

Is not this the Christ? - Though she probably believed it, yet she proposed it modestly, lest she should appear to dictate in a case which was so important, and which demanded so much attention. The evidence on which she was satisfied that he was the Messiah was that he had told her all things that she had done - perhaps much more than is here recorded. The question which she submitted to them was whether this was not satisfactory proof that he was the Messiah.

4:29 A man who told me all things that ever I did - Our Lord had told her but a few things. But his words awakened her conscience, which soon told her all the rest. Is not this the Christ? - She does not doubt of it herself, but incites them to make the inquiry.