Would You Know The Devil When You Had Seen Him?

No, because he is a trickster, and a coward, he wouldn't show himself. Well, that is what I think.

Actually, Fred Goodwin looks just like a normal person................

Seriously though, the chance of the Devil actually existing as a real being is about as likely as God, i.e. Vanishingly unlikely.

Probably not until it's too late. Hopefully my faith in THE LORD would be strong enough at the time for me to realize what is happening and the devil would just run away because he is afraid of the truth which is what defeat him in the end

Maybe,but I doubt it,he's a trickster.