The big striker pounced from six yards with just two minutes left to give the Cumbrians a deserved point.
Carlisle ran Shrewsbury ragged in the second half but could not find a breakthrough, mainly due to the heroics of Shrews keeper Joe Hart.
A Valentine's Day massacre had looked likely when Chris Lumsdon volleyed home for the home side after only 90 seconds.
But the lead was short lived and Shrewsbury hit back 10 minutes later with their first shot on target.
A poor clearance by Carlisle fell to Neil Sorvel 20 yards out and he hit the perfect half-volley that flew through the crowded penalty area and past the helpless Keiren Westwood.
Colin McMenamin went close for the visitors but Zigor Aranalde was unlucky to see his header hacked off the line by Kevin Sharp.
The Cumbrians started slowly in the second half but despite easing into top gear the Shrews' defence held firm.
A series of Carlisle penalty appeals were turned down by referee Jonathan Moss and with little going the home side's way they should have expected what was to come.
A goal duly arrived for the visitors with just their third shot on target when another Sorvel long effort was turned past Westwood by Richard Hope.
Carlisle felt aggrieved and two glaring misses by Adam Murray only added to their woes.
But with just seven minutes left the gods took pity on Carlisle when the referee awarded a penalty under bizarre circumstances.
Aranalde's header was saved by Hart and defender Ben Herd blocked on the line. Then, with the linesman waving for a goal, the referee decided instead to point to the spot and sent off the furious Herd.
Lumsdon stepped up but could only look on in horror as his penalty was saved at full stretch by Hart.
The Shrews looked likely winners until Holmes broke their hearts with just two minutes left.