Atheism is the default position. Isn't the burden of proof on the Christian to assert that God exists? The title is a bit tongue in cheek, but according to Christianity, is it necessarily right to have to make arguments starting from atheism? It seems obvious to me that God exists. However, in both causal arguments, or public policy, this seems the default position ingrained in our culture and to make an argument otherwise is ridiculed.

Is this a legitimate premise (that atheism is the default position) to reason from? I think not, but what are the arguments against it? With what methods of reasoning does Christianity approach this issue?
Christian apologetics often employ a form of presuppositional logic. In fact, the wikipedia page for Presupposition (philosophy) specifically addresses this issue:


  A variety of Christian apologetics, called presuppositional apologetics, argues that the existence or non-existence of God is the basic presupposition of all human thought, and that all men arrive at a worldview which is ultimately determined by the theology they presuppose. Evidence and arguments are only marshalled after the fact in an attempt to justify the theological assumptions already made.


It is difficult or impossible to coherently reason with someone who makes different presuppositions than you, and sometimes the best course is to first lay out your presuppositions. After you have a place to stand on, you can look back and defend those views.

The Biblical witness on this point is fairly straightforward. God exists. In addition to this testimony it claims that there is no possible excuse for men not knowing at least some basic facts about his identity.


  Romans 1:20-21 (ESV)
  20&nbsp; For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse. 21&nbsp; For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened.


After asserting in verse 20 that there is clear evidence in the world pointing to some attributes of God, verse 21 goes on to state that all men knew God and that it is through willfully not honoring him As God that they become unable to reason properly. Without a worldview informed by the presupposition that God exists, as well as certain attributes about him, men are unable to see clear reason.

The writer C.S. Lewis applies this idea to practical belief and frames it in layman's terms rather graphically when he wrote:


  "I believe in Christianity as I believe that the sun has risen. Not only because I see it, but because by it I see everything else."


To Christian reason, no further proof of God's existence is required but that, knowing he does exist, we can finally make sense out of the world around us.