The Croatian had already described Messi as "miraculous" ahead of the 2014-15 campaign but, with La Liga now under way, he has confidently described the four-time Ballon d'Or winner as peerless among any footballers ever.
"The team's brilliant, really awesome," the 26-year-old told reporters at a press conference on Thursday. "We must not relax and enjoy it though."
"I always see Messi at his very best, there's hardly any need to talk much about him. He's the best in the world and the best in the history of football."
Rakitic also commented on another Camp Nou legend, Xavi, whom he was chosen by coach Luis Enrique to start ahead of in Barca's opening match of La Liga's season last Sunday.
"We all know what a player Xavi is and he's a presence in the locker room," he added. "He is an idol and I'm enjoying training with him, every day is learning curve.
"It's true that we all want to play but the coach has the decision on that. I'll just try to give everything to help on the pitch."
Rakitic, signed from Sevilla, was one of many new additions at Camp Nou this season as Barca look to make amends for a 2013-14 in which all the team won was the Supercopa.
Barca visit Villarreal on Sunday as they look to build on last weekend's 3-0 win which gave them a lead in La Liga as of matchday one.