The Belgian international has scored 14 goals this season since his £8m move from Genk and he has almost single-handedly propped up Villa's ailing league campaign.
"When the guy came in people were saying to me: 'Who is he and why are you going for someone from Genk?' With what he's done he's a cult hero.
"He's only 22 and he's got years and years ahead of him. He's not at his peak, but what he's done for me and for the club is fantastic.
"If someone wanted to buy Christian they'd better have a few quid in your pocket to buy him. He's not just going to walk out of here for the value he came for, that's for sure.
"We have given him the opportunity to show what he can do and I think he is loving his football at the moment.
"I've heard the whispers about what he's supposed to have said. To me, it's funny because he doesn't speak!
"I've heard nothing. He's a cracking big guy and really humble. If he keeps that he could be anything he wants to be."