Messi, who will miss the next two months of the season with a hamstring injury, is 'relied on' at the Catalan outfit, according to the Spanish stopper.
"Messi is the best, for me Messi is God. He is the best and always will be, for what he has given the team and what he has allowed me to enjoy as a teammate," he told reporters at a press conference.
"For me, Barca will always be dependent on him because he is the best in the world. And because I suffer as a teammate in training. He knows that the team relies heavily on him. I see him sad. By default players are selfish and do not understand the inability to play the game.
"Knowing him and knowing his winning attitude, I have no doubt that he will do his part, which in fact he is already doing."
Valdes will leave Barcelona on a free transfer next summer.