That's an easy one. First you say "Carbon Dating is dependent on the amount of sunlight. The Water Canopy before the flood affected the amount of sunlight, thus throwing off the modern-day assumptions about carbon dating."
Then the atheist retorts that that carbon dating is only useful for dating in the past 60,000 years (AND that variations of carbon in the atmosphere are calibrated with tree rings), and that there are other radioactive clocks with much longer half lives for dating older samples which are not dependent on the amount of sunlight.
So at that point you say "I believe the Bible, Evolution is only a theory, Do you think the people who created the fire came about by chance?, Maybe lightning hit some logs that an animal was sitting on, etc."