I laugh harder when some Christians claim to understand the Bible any better. It's clear many of them haven't even read the whole thing. One such Christian even admitted to that on this forum.
What many who make these types of statements fail to realize is that many of us atheists used to be hard core Christians. In fact, many of us deconverted entirely because of our desire to be better Christians. Really looking into the make up of the Bible, it's history, and actually reading what's in it can be quite eye opening for those who dare.
But hey, if it makes you feel warm and fuzzy to think you've got it all correct, enjoy. It's pretty clear in some of these debates who has done their research (on both sides) and who hasn't. One might notice the solid Christian debaters don't make these ridiculous statements because they know better. It only seems to be the weaker debaters that have no substance to their claims that have to resort to mud slinging and claiming "those darn atheists have no clue about the Bible".