Or more correctly, "Based on a certain fundamentalist literal interpretation of Genesis 1 & 2, to which I adhere, I believe the world is around 6,000 years old, in spite of the physical evidence."
Most Christians who hold to a literal interpretation of Genesis 1&2 (and other Scripture) have their roots in the teachings of those coming out of Dallas Seminary (which is Darby/Scofield dispensationalism to the core.)
If you ever decide to expand your horizons, here are some resources:
McGrath (Christian) takes on Dawkins and his religion (Scientism):
Do stop behaving as if you are God, Professor Dawkins By ALISTER McGRATH
This is the best book on the market specifically providing a critique of Richard Dawkins' view that science in general, and evolutionary biology in particular, can be used to support atheism. McGrath was himself a committed atheist when he came up to Oxford as a student, before then becoming a Christian. McGrath did a PhD in molecular biophysics before later turning to theology, and is therefore in a strong position to analyse Dawkins' views, which he does carefully and objectively. The philosopher Michael Ruse writes that this is "A wonderful book...This is scholarship as it should be - informed, feisty, and terrific fun. I cannot wait to see Dawkins' review of Alister McGrath's critique". Francis Collins, Director of the Human Genome Project, writes: "Wielding evolutionary arguments and carefully chosen metaphors like sharp swords, Richard Dawkins has emerged over three decades as this generation's most aggressive promoter of atheism. In his view, science, and science alone, provides the only rock worth standing on. In this remarkable book, Alister McGrath challenges Dawkins on the very ground he holds most sacred -- rational argument -- and McGrath disarms the master. It becomes readily apparent that Dawkins has aimed his attack at a naive version of faith that most serious believers would not recognize. After reading this carefully constructed and eloquently written book, Dawkins' choice of atheism emerges as the most irrational of the available choices about God's existence.v