According to the dictionary, deception is the art of making someone believe something that is not true. So, when you are deceived, you believe a lie.
The thing about deception is that when you are deceived, you don’t know you are being deceived. Deceived people think they are believing the truth, but in fact they have been sold a lie. You see, deception always has an element of truth in it. If it was a total lie, no one would believe it. So it is usually truth mixed with error.