it will to a degree. Short focal length + wide aperature = gobs of light = shorter shuter speeds and better low light performance.
However a 1.8 or 1.4 wont work miracles, if the light is low it is low.
The fact is, tghe bride and groom are going to have to either choose a well lit area, or allow the photog to bring in lights, or use a flash.
bring in a couple of these babys. Just got them in. They slave off your camera flash or a pc sync