The origin of the gesture traces back to the biblical Kingdom of Israel. Courts of Mosaic law would often render verdicts with the phrase "May God have mercy upon your soul '' in order to reaffirm God 's supreme authority over the law. Most judges felt that while they could pass a sentence of death upon a person, they personally did not have the authority to destroy souls and that only God had the authority to do that. As a result, some judges would cross their fingers whenever they said the phrase as a result of concern for the criminal 's soul as they said it as a prayer.
where did crossing your fingers for good luck come from
the biblical Kingdom of Israel