When someone tries to say that the Iraq insurgents are beating us, they may use examples of violence such as this to bolster their claim:
Sadrist lawmaker Qusai Abdul-Wahab blamed U.S. forces for Thursday's deadly attack on Sadr City because they failed to provide security. Suspected Sunni insurgents killed 215 people in the Shiite slum with mortars and five car bombs in the deadliest attack of the war.
As Vice President Dick Cheney traveled to the neighboring Sunni country of Saudi Arabia on Saturday to seek help in calming Iraq down, Iraq's sectarian violence shifted to Diyala province north of Baghdad, where gunmen broke into two Shiite homes and killed 21 men in front of their relatives, police said. U.S. and Iraqi forces also killed 58 insurgents during fighting in the same region.
These examples do not prove the enemy is winning, only that they are willing to kill in order to win.
You also have to consider that attacks like these are part of a Sunni-based insurgency strategy of trying to get the Shias to retaliate against the Sunnis. Why would Sunni terrorists try to get Shias to kill Sunnis? Because the Sunni terrorists know that most Sunnis don't support the Sunni insurgents. The insurgents hope to drive Sunnis into supporting the insurgency as the only means of protecting themselves against Shia attacks.
Unfortunately for the prospects of ending the insurgency, the Sunnis have succeeding in making the Sunni leadership too worried about Shia death squads to make a deal with the Shia-dominated government.
And also unfortunately for the Sunnis, siding with the Sunni terrorists won't protect them--it will just guarantee that the Shias kill all the Sunnis or drive them from central Iraq to Anbar province or even drive them from all of Iraq.
The Sunnis really need to just surrender and hope that our presence can somehow restrain the Shias from carrying out large-scale revenge attacks for all the past Sunni crimes against the Shias. Continuing to fight is no real option for the Sunnis. But given how poorly they have chosen so far, I have little hope they will suddenly rub a couple brain cells together and spark a smart move to end their futile war.