The imposing front-man, 22, has been a shining light since joining from Belgian side Racing Genk in August.
Benteke's first season in England has yielded 14 goals in all competitions, including five in his last four games, and his performances have given the under-fire Lambert a huge boost as Villa battle for survival.
"When the guy came in people were saying to me 'who is he and why are you going for someone from Genk?', Lambert told the club's website ahead of Sunday's league clash at home to West Ham United.
"With what he's done, I think he's a cult hero."
Benteke scored on his Villa debut as a substitute and his effectiveness has kept record signing Darren Bent on the bench for large parts of the season.
Lambert said Benteke would keep on improving.
"He's not at his peak. But what he's done for me and for the club is fantastic," said the manager.
"We have given him the opportunity to show what he can do and I think he is loving his football at the moment.
"He's a cracking big guy and really humble. If he keeps that he could be anything he wants to be."
Villa, without a league win since December 15 - a run of eight games - are desperate for three points against West Ham having slipped into the relegation places.
Lambert's side are 19th with four wins from 25 games. Only bottom side Queens Park Rangers have a poorer return.
Benteke was still a Genk player when West Ham beat Villa 1-0 at Upton Park on the opening day of the season and manager Sam Allardyce said he would pose the "biggest threat" to the goal-shy travellers who have just two wins on the road in the league.
"He's the man who scores the goals for Aston Villa on a regular basis, he's the focal point for their attacks in that he not only scores goals, but he holds the ball up, he's strong," Allardyce told West Ham's website.
"He's had a fantastic start in what must have been a very disappointing season so far for Aston Villa."
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