The Selecao will play their semi-final against the Germans on Tuesday without their star man after he suffered a fractured vertebra in a clash with Juan Camilo Zuniga in the 2-1 quarter-final win over Colombia.
Raul feels the absence of the 22-year-old forward, who has scored four times in the competition, along with the suspension handed to captain Thiago Silva will leave Brazil far weaker.
"Neymar is out of the World Cup with a broken vertebra, and that means they will be half the force when they line up against Germany on Tuesday," the 37-year-old wrote in his column for the Times of India.
"On top of that, defender and captain Thiago Silva are suspended. So they will miss two of their most reliable performers in two key departments.
"It's terrible from a Brazilian perspective because Neymar was the only one in their forward line who looked threatening.
"Although he didn't have a great game against Colombia, players like him can come alive like a spark and change the course of a match in an instant.
"Missing him against Germany is a massive blow but that's life and football. His team-mates will have to give everything that they have and see if they can win it for him."
However, Raul, who played in three World Cups for Spain between 1998 and 2006, did concede that the Verde-Amarela looked more assured against Colombia and look to be improving as the World Cup progresses.
"Brazil showed a lot of urgency and Colombia fizzled out after promising much in the previous matches," he continued.
"The Brazilian midfield functioned better in taking the game to their rivals and the team did well to sustain pressure in the attacking third.
"They managed to keep Colombia on the back foot for a long time and it's good from their point of view that the central defenders scored when the strikers got stuck.
"Their defence did a steady job in the later stages and will have to keep it up against a very strong German side."