“Father forgive them, they know not what they do.”
When I was a kid my father had a saying, “It's easier to get forgiveness than permission.” He would use this proverb whenever he believed there to be extenuating circumstance, uncertainty or exceptions concerning that might allow him to exceed the speed limit or go up the down escalator. Of course, every time I attempted to apply this saying as a child, I found both forgiveness and permission to be equally elusive. I was often met with the chiding, “you should know better.”
Israel should have known better. They had no reasonable excuse for crucifying anyone, let alone their Messiah. And yet Christ suggests that they be offered leniency on the grounds of ignorance.
We all require grace on the basis of ignorance. Just like Israel, none of us fully recognize the glory of the Lord Jesus Christ. Despite having the Scriptures, the Holy Spirit and the totality of nature revealing to us the preeminence of Christ, we still seem to think that there are also other things going on in this world outside of Him and that these other things are what matter. None of us know what we do, Father forgive us all.