The Pulpit Commentary on John 10:25

Jesus answered them. The reply of Jesus is full of wisdom. If he had at once given an affirmative answer, they would have misunderstood him, because he was not the Christ of their expectations. If he had denied that he was the Messiah, he would have been untrue to his deepest consciousness of reality.

The answer was: I spake with you—told you what I am—and ye believe not. To the woman in Samaria, to the Capernaites, to the blind man, to Peter and the other apostles, and in several emphatic forms, he had admitted his Messiahship.

In John 8:1-59. he had claimed the highest honors and announced his [Divine commission, and appealed to his great Messianic works, but his endeavor to rectify their Messianic ideal had, through their obtuseness, failed of its purpose.

So now once more he referred them to works done in his Father's name, which hitherto had failed to convince them: The works that I do in my Father's name (John 5:19, John 5:36), they bear witness concerning me.