So here is a very smug creationist talking about why Atheism is an irrational standpoint.
Sound reasonable? Sound like he knows what he's talking about? Sound even slightly philosophical?
Here's the deal. Atheists do not claim that there is NO God. Your initial definition of atheists is wrong. Atheists are not "[individuals] who decide to believe against the idea of a deity".
This can be seen to be for tactical, and logical reasons. Tactically, if an atheist claims that there is no God, then it is up to the atheist to provide evidence to back that claim up. Which is impossible. Logically, you cannot claim to absolutely know that there is no God (just like you cannot claim to absolutely know that there is a God without extraordinary evidence). So yes theTRUTHgroup is right in that respect, that one must be omniscient in order to claim with absolute certainty that there is NO God.* However this does not make the person a God. It is rational to say that someone could have omniscience without being the creator of the universe. And even if you don't claim God to mean THE creator, you would not go attributing the title of God to anyone who developed extreme super powers!
Ultimately what this post boils down to is that atheists do not claim to know there is no God. A more appropriate definition for an atheist is a person who lacks a belief in God. For those who may be confused, the difference is that theTRUTHgroup's claim was that atheists believe there is no God, and so are asserting a claim. On the other hand the more accurate definition of the Atheistic position is that atheists have no belief in the existence of God, and so they are not asserting a claim.
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*Omniscience may not even be compatible with the idea of the Creator God. A creator God must be omnipotent in order to create the universe, however omniscience may not be necessary. The creator God could know everything about creating the universe but not about everything else. The incompatibility between the two stems from this paradox (similar to that of the time traveler's paradoxes):
If God is omniscient He knows everything He will ever do and think. Yet if He is omnipotent He must be able to change what He is able to do and think. Yet if He changes what He does and thinks, since He is omniscient He must have already known He was going to do that... etc.
