G. K Chesterton and the evidence for the virgin birth

When G. K. Chesterton was arguing against a rationalist who denied miracles on the ground that experience is against it, he cited this:

There was a great Irish Rationalist of this school who, when he was told that a witness had seen him commit a murder, said he could bring a hundred witnesses who had not seen him commit it. (Gilbert Keith Chesterton, 176)

Anybody ever told you that it couldn't possibly have happened that way just because they've never seen it done?