Means absolutely nothing to me what age a Christian believes the earth to be.
I'm a theistic evolotionist (is that the right word??). I think the theory of evolution is a possible theory for "How God Did It". We probably will never know for sure, this side of Heaven, HOW God created the universe, our world, us, etc. and IMO, it's not necessary for our Salvation to know for sure. What we DO need to know is that He sent His Son, that He died for us, and that all of us can recieve forgiveness if we believe on His Name.