Sorry, physics loser talking there.
The 2nd law is the 2nd Law of Thermodynamics, which basically states that the entropy of a system increases if the system is changed by an irreversible process.
To you and me this means this become more disordered as time goes on, be they bedrooms or universes. [in a closed system]
Mad creationists use it to say that evolution couldn't work because it's complexity emerging over time not disorder, but this is false because the system in question is not closed, that is there are external forces like gravity bringing things together.
The 2nd law is what gives time its "arrow" or direction. Basically we can tell which way time is going by looking at the increase in entropy of a system.
As for the rationality of all this, I'm just wondering about some books I'm reading, as well as your personal views.
You claim you're an atheist? Yes? Or did I dream this up somewhere? For the minute I'm not going to bring any particular religion into the equation, I'm just intrigued by what you support your argument of "no God" with. Anyway, get back to me when you can, if you want a better explanation of the 2nd Law I'll dig it out for you, although http://www.entropysite.com/students_approach.html is a good start.
Cheers
Nick