literal... i can't think of any specific examples... but i can think of that one dudes shadow who passed over and healed a person. at least i think thats how the story went. so i figure if a shadow can do it then a hand can do it for sure and the shadow kinda one upped the hand.
Yes, there are snake handlers in the group of believers, so yes, you could say that sign has "followed". Sometimes, they get bitten and sometimes they die, but that wasn't mentioned as part of the sign, so if we're being literal, I'll have to say yep, that's a sign alright!
As for drinking any deadly thing, however, it does say "it shall not hurt them." This sign is on shaky ground, since sometimes those who drink a deadly thing do get sick, and some die. If we are to take this list seriously, we must conclude that the world has not yet seen that group of believers, and recognized them as such by virtue of that sign following them -- unless you know of such a group? Where it's actually true that if they drink any deadly thing, it shall not hurt them?
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Hebrews 13:23 Know ye that our brother Timothy is set at liberty