I am not trying to convince the person I am talking with to my side of the argument rather it's the audience. When people sit back and say your wrong because of X, Y and Z others see this as a demonstration of conflict so both sides could be right. But, when people say "the world is 6,000 years old" and you respond with "Did the talking snake tell you that?" it works on a different level.

Take global worming there is a manufactured debate on the issue and few people are willing to say, "Ok, smart guy how should we rewrite the laws of physics?" Or, letting people say "Clean Coal" like there is such a thing when they can say, "Ok, I agree that Clean Coal is great let's mandate zero CO2 emissions from coal in 5 years." so they need to say, "Well we don't have the ability to do that."