Answer:
I'm not quite sure but I might
Hale wants John to prove his Christianity, and his loyalty to God. In a chaotic time, driven by the hysteria of witchcraft, Hale and the court want to eliminate those reached out to by the Devil. However, as John has not been to Church for a long period of time, he evidently cannot name all 10, and falls on 'Thou shall not commit Adultery'- ironic, as he broke this very commandment.
