I Don't Know about Agnosticism
I don't know if Mr Cru will buy me any Christmas presents, but I expect he will and I live my life assuming he will (i.e. by buying him some), I don't know if the next person to ring my doorbell will be coming to murder me, but I expect they won't (so I answer the door). In fact when it comes down to it I barely KNOW anything. We live our lives based on probabilities.
The evidence against God's existence is overwhelming, from the fact that globally almost all the major religions are totally incompatible to the extensive fossil record to the bizarre fact that all the so called "miracles" in the bible sound a great deal like natural disasters we can now explain scientifically. We may never know for 100% certainty that there is no God but we already know with 99.999...% certainty and we're getting more and more evidence all the time.
The trouble is when people say they are agnostic they seem to be saying that God's existence is 50-50, that the arguments for both sides are equally strong. From everything I've heard and read in my life there are no convincing arguments for God's existence. Accepting the idea that there is something intellectual about sitting on the fence is only going to slow scientific progress down.