I was thinking about the question presented on this thread and I think it depends on how we define "sin".
For example, some would say that due to the internets vile contents and some banner adds on just news websites a Christian is in sin by merely having access to it in the home. I was on CNN website and saw a very nice Victoria's secret add... and forgive me, I'm a healthy man, and it appealed to me. Some would say I sinned by looking at it.
So I think "sin" needs to be defined. Once sin is defined we can determine if we can live a sinless life.
By the way, personally, I think we can.