Since I'm going to be writing about atheist arguments I'd like to kill, I thought it wise to first discuss an issue other atheists have had with some of MY past arguments. Occasionally, in debates with generalized theists (I don't budge an inch for fundamentalists; they have a loooooong way to go before any argument made will make a dent in their irrationality), I will grant their deity of choice the favor of presumed existence.
For example, when dealing with a christian who is insisting that the Second Law of Thermodynamics makes evolution impossible, I might respond that, applying the law in the same way they are, the Second Law of Thermodynamics also makes the eternal fires of hell impossible, so we must be leaving something out of the equation. I then go on to explain that the eternal fires of hell are possible because the Second Law of Thermodynamics only applies to closed systems, but that hell is exposed to the omnipotent power of God - God's will that hell keep burning, in essence, provides the fuel that invalidates the Second Law where hell is concerned. I then go on to explain that the Earth isn't a closed system either, that it's exposed to the power of the sun and that the sun provides the fuel that invalidates the Second Law where evolution is concerned.
Most atheists are willing to play the "let's pretend your god exists" game, but applying physics to the concept of hell in a positive manner is a step too far for many of them. The main criticism levied against me is that by giving serious consideration to a clearly mythical concept, I'm solidifying the faulty notion that, deep down, atheists know God exists and are merely in denial. My defense to this charge is two-fold:
1 - No Christian who truly believes in hell is going to be able to reconcile the concept of a loving god condemning nice people to eternal torment without the assistance of Romans 1 (the verses that assert all humans know god exists).
Romans 1 is the anal lube of eternal damnation - believing that people you love will exist in a state of perpetual torment hurts, but it hurts a little bit less if you also believe they chose that fate for themselves. Nothing I could ever say or do would give Christians more reason to believe in the validity of Romans 1 than their own need to see God as something other than an abhorrent monster.
2 - It works.
The vast majority of individuals I presented with this argument retired the "Second Law of Thermodynamics makes evolution impossible" assertion from their arsenal of ridiculousness (at least in further discussions with me). Suggesting that, because their belief in hell must be right, their understanding of physics must be wrong, allows the believer to correct their understanding of thermodynamic law without undermining their faith.
Essentially, I feel that it's appropriate to use a believer's faith against them by calling forth their own superstitions and using them as weapons. What do you think? Is it appropriate to presume the existence of a deity for the purpose of debate?