After seeing Padraig Amond earn the Shrimps the three points with a goal six minutes from time Bentley said: "I can't believe the spirit and determination that these lads have.
"At half-time we were three goals down to a side who I thought were outstanding.
"But we have come from behind a few times this year and I told them at half-time that if they got an early goal the game wasn't over.
"We did just that and it changed the game dramatically. We played some superb stuff after that and the crowd got right behind us and every time we went forward we looked dangerous.
"At the start of the season we were tipped to be one of those teams who were favourites for relegation, but I always said that this bunch of lads has a spirit that money can't buy and they have proved that again."
Chesterfield looked set for the three points after a dream start with two goals from Eoin Doyle in the fourth and 22nd minutes and one from Gary McSheffrey after 10 minutes gave the Spireites the advantage.
Morecambe were given a brief glimmer of hope when Kevin Ellison pulled one back 40 seconds into the second half.
When home skipper Mark Hughes scored a second on the hour-mark the game became even more interesting.
With Morecambe finding new belief Jack Sampson poked home Ryan Williams's far post free-kick to bring the sides level and the comeback was complete when with six minutes to go Padraig Amond headed Sampson's left-wing cross past Tommy Lee to seal a remarkable second-half show from Bentley's side.
Chesterfield had chances of their own to score a fourth with Jay O'Shea firing wide from a good opening and Barry Roche saving well to deny Doyle his hat-trick as Cook's side slipped to a second successive defeat.