The 34-year-old midfielder, who has made 113 appearances for England, said Italian Capello had transformed the mentality of the squad less than two years after Croatia won 3-2 at Wembley and denied the side a place in Euro 2008.
Capello took over after that failure and a revitalised England lead European qualifying Group Six with a maximum haul of 21 points from seven wins and will make sure of their place in next year's World Cup finals in South Africa if they beat Croatia at Wembley on Wednesday.
"What Fabio Capello has brought back into the squad and also back into the nation, is the belief," Beckham told reporters at England's team hotel.
"After failing in the last qualifying campaign, the belief and the trust went from the fans and that hurts the players more than anything.
"But what this manager has done is brought the belief back for the fans and the belief back into the players and that's what we needed. We are playing good football again.
"The fans might be wanting us to beat Croatia and gain revenge," said Beckham, "but the most important thing for us is going into the game knowing if we win it we are in the World Cup finals, that's all the players and staff are thinking about.
LOWEST POINTS
He said losing to Croatia was one of the lowest points in his England career, adding: "No-one in that dressing room will ever forget that night. It was a tough time for everyone, but now, we are not looking for revenge. Our incentive is to reach the World Cup finals."
Beckham, who is no longer an automatic starter for the national side and did not come off the bench during the 2-1 friendly win over Slovenia at Wembley on Saturday, would become the first English player to appear in four World Cups if he plays in South Africa.
One man who is virtually guaranteed a starting place is Frank Lampard, who won his 73rd cap and scored his 18th England goal in Saturday's friendly.
Lampard laughed off comments by Croatian coach Slaven Bilic, that England had lost their competitive edge, or their "Englishness" ahead of Wednesday's match.
"I don't know what he's talking about," said Lampard. "He's a very good manager and a very clever man, but I don't understand that. Of course we are competitive. We want to win and get to the World Cup as quickly as possible."
Beckham added: "We might have an Italian manager, but he's got an English mentality and so have all his staff. He wants to win and so do we."
