Why were people willing to believe that Voldemort was back at the Quidditch World Cup?

Question

In The Order of the Phoenix most of the wizarding community don't believe that Voldemort is back. Lupin says that many people didn't believe because they didn't want it to be true.

"While the Ministry insists there is nothing to fear from Voldemort, it’s hard to convince people he’s back, especially as they really don’t want to believe it in the first place."
_{(Order of the Phoenix, Chapter 5, The Order of the Phoenix).}

Yet at the Quidditch World Cup, when the Dark Mark was projected into the sky, people seemed quick to suggest that Voldemort might be back (even when he in fact wasn't).

But when they reached the edge of the wood, their progress was impeded. A large crowd of frightened-looking witches and wizards was congregated there, and when they saw Mr. Weasley coming toward them, many of them surged forward.
“What’s going on in there?”
“Who conjured it?”
“Arthur - it’s not - Him?”
“Of course it’s not Him,” said Mr. Weasley impatiently.
_{(Goblet of Fire, Chapter 9, The Dark Mark).}

If people were unwilling to believe that Voldemort had really returned then the appearance of the Dark Mark should be no cause for concern. Yet at its appearance "the wood all around...erupted with screams". The Daily Prophet put the Mark on its front page under the headline SCENES OF TERROR AT THE QUIDDITCH WORLD CUP.

What can explain the two polar opposite responses within the space of a year? In one instance there's blind panic at the appearance of Voldemort's sign; in the other there's stubborn refusal to accept the facts even when an eye witness says that he's returned.

Answer 1

People panicked because of things they saw.

Children were spinning like tops sixty feet above ground. Muggles were being insulted. Tents were being set on fire.

Two of the figures were very small. More wizards were joining the marching group, laughing and pointing up at the floating bodies. Tents crumpled and fell as the marching crowd swelled. Once or twice Harry saw one of the marchers blast a tent out of his way with his wand. Several caught fire. The screaming grew louder.

The floating people were suddenly illuminated as they passed over a burning tent and Harry recognized one of them: Mr. Roberts, the campsite manager. The other three looked as though they might be his wife and children. One of the marchers below flipped Mrs. Roberts upside down with his wand; her nightdress fell down to reveal voluminous drawers and she struggled to cover herself up as the crowd below her screeched and hooted with glee.

“That’s sick,” Ron muttered, watching the smallest Muggle child, who had begun to spin like a top, sixty feet above the ground, his head flopping limply from side to side. “That is really sick...”

_{^{Harry Potter and the Goblet of Fire, Chapter 9, The Dark Mark}}

And finally the dark mark appeared, the symbol of Lord Voldemort.

For a split second, Harry thought it was another leprechaun formation. Then he realized that it was a colossal skull, comprised of what looked like emerald stars, with a serpent protruding from its mouth like a tongue. As they watched, it rose higher and higher, blazing in a haze of greenish smoke, etched against the black sky like a new constellation.

Suddenly, the wood all around them erupted with screams. Harry didn’t understand why, but the only possible cause was the sudden appearance of the skull, which had now risen high enough to illuminate the entire wood like some grisly neon sign. He scanned the darkness for the person who had conjured the skull, but he couldn’t see anyone.

“Who’s there?” he called again.

“Harry, come on, move!” Hermione had seized the collar of his jacket and was tugging him backward.

“What’s the matter?” Harry said, startled to see her face so white and terrified.

“It’s the Dark Mark, Harry!” Hermione moaned, pulling him as hard as she could. “You-Know- Who’s sign!”

_{^{Harry Potter and the Goblet of Fire, Chapter 9, The Dark Mark}}

The Dark Mark generally meant somebody was murdered!

“And it hasn’t been seen for thirteen years,” said Mr. Weasley quietly. “Of course people panicked... it was almost like seeing You-Know-Who back again.”

“I don’t get it,” said Ron, frowning. “I mean... it’s still only a shape in the sky...”

“Ron, You-Know-Who and his followers sent the Dark Mark into the air whenever they killed,” said Mr. Weasley. “The terror it inspired... you have no idea, you’re too young. Just picture coming home and finding the Dark Mark hovering over your house, and knowing what you’re about to find inside...” Mr. Weasley winced. “Everyone’s worst fear... the very worst.”

_{^{Harry Potter and the Goblet of Fire, Chapter 9, The Dark Mark}}

When Voldemort actually returned, Harry saw it. Nobody else saw and the ministry went into denial.

“Voldemort doesn’t march up to people’s houses and bang on their front doors, Harry,” said Sirius. “He tricks, jinxes and blackmails them. He’s well-practiced at operating in secret. In any case, gathering followers is only one thing he’s interested in. He’s got other plans too, plans he can put into operation very quietly indeed, and he’s concentrating on those for the moment.’

_{^{Harry Potter and the Order of the Phoenix, Chapter 5, The Order of the Phoenix}}

People thought Voldemort was back when they saw his symbol, the Death Mark. But when he actually returned most folks did not see it and did not believe Dumbledore's words because it was easier to be on denial.

Answer 2

They were panicking. In book 5, when he really was back, they had thought about it and were scared enough that they decided that he wasn't back. However, when they saw the Dark Mark and the Death Eaters torturing the Muggles, they had no time to think. To them, that meant not that Voldemort was back, but simply "run."

Also, you have to admit that the evidence at the World Cup is much more solid than that in book 5. On one hand is the Dark Mark and a bunch of Death Eaters torturing people--on the other hand, an attention-crazed teenager and a crazy old man.

---

I never thought that the people ran because Voldemort was back, just because of the commotion. Tents were burning, Muggles were up in the air--this was basically a terrorist attack. And when a terrorist attack comes, you don't stop to think what's causing it. You run, you scream, and you print it in the next morning's paper. And that's what they did. Also, the Death Eaters were drunk.

---

Would you not run from this and scream?

More wizards were joining the marching group, laughing and pointing up at the floating bodies. Tents crumpled and fell as the marching crowd swelled. Once or twice Harry saw one of the marchers blast a tent out of his way with his wand. Several caught fire. The screaming grew louder.