It feels self-evident that it would be Very Bad. Even just all of the solar energy that hits the Earth (a fraction of what the sun puts out) would be Very Bad, if it was concentrated into one spot.
The dire fate of the earth seems pretty obvious here. I'm more interested in what would happen to the sun in that scenario. If all of its radiating energy was focus down to a narrow beam pointing in one direction, wouldn't that push it in the opposite direction?