It's one thing to say we beat Spain, its another to use that victory as premise to validate confidence if we were to play them again. To do that, you need to expand your perspective to more than just the score line and review the game as a whole.
Spain had enough chances in the second half to not only draw the game but to win it by a margin. When you play sides that keep the ball for the majority of the game, you need to ask yourself whether your defence can handle them. Can England's defenders be confident against Spain? I don't see how. England would need to be at their best and hope luck is on their side. To suggest that result in November act as evidence to a strength is just something beyond comprehension IMO.