If you have ever had a conversation with a creationist of the "young earth" variety (who believe the entire universe is less than 10K years old, with all species created by God as described in Genesis), you'll know it is a frustrating experience.
Point to the fossil record, say, or light from distant stars, or carbon dating, or tectonic plate movement, etc. as evidence of a much older universe, and you will find they have prepared answers, supplied, for example, by the multi-million dollar funded Institute for Creation Research.
There are also innumerable creationist resources on the web, such as at www.christiananswers.net.
I'd like to discuss how best to respond to young earth creationists when you come across them (I've come across quite a few in British Schools, recently - including one teaching science in a leading public school).