What religion is associated with fingers crossed and knock on wood?
I am with you, never heard of it being associated with a religion.
I’m no expert on ancient hand gestures but a quick google search popped up lots of articles linking it to Christianity and to its Cross, here’s one:
“Although crossed fingers are a pretty recognizable gesture, their roots in Christianity help us understand why it isn't a worldwide belief.”
https://www.refinery29.com/fingers-crossed-meaning-good-luck-superstitionAlso, most OJ refrain from using a cross in any way shape or form, so even if you’ll find a guy with a PHD in hand gestures (I know, would be the saddest use of human brain cell ever recorded, but nevertheless) and he’ll tell you that truth be told fingers crossed is in no way linked to any religion, it would still be a questionable gesture for Jews, particularly OJ.