In my interactions with atheists, one of the most common tactics I have observed is the claim that atheism is not a worldview. Atheism is not belief, but the absence of belief. It is not a claim, but the absence of a claim. Therefore, or so it goes, atheism does not need a defense. Another interesting tactic employed by atheists is the move to redefine it. Atheism does not claim that God does not exist, but merely claims that there isn’t enough evidence to support the belief that He does. What is a Christian to do? How is should we think about these tactics? The goal of this post is offer some suggestions for how you might think about these tactics, and from that thinking, how you might respond or challenge an atheist who happens to be employing them.
First of all, what is a worldview? A worldview is any paradigm that rests upon basic presuppositions that serve to inform how you interpret, understand, or view the world, or this reality in which we find ourselves. Worldviews typically seek to answer basic questions about the nature of reality, knowledge, and morality. So, the question would be simply this: does atheism seek to answer questions about the nature of reality, the nature of how human beings know things about that reality, and the nature of right and wrong? It seems uncontroversial to me that atheism denies that this reality is the product a supernatural act performed by God, that human knowledge is the natural operation of the human brain, and that right and wrong can be known without reference to a transcendent being. By simple definition, atheism is a worldview and ought to be treated as such. That there are various theories regarding metaphysics, epistemology, and ethics within atheism does not ipso facto rule it out as falling within the definition of a worldview.
The second claim is that atheism is not a belief, but a lack of belief. Atheism is not making any claims. The Christian ought to ask if such a situation is possible. Atheism, like other systems not only includes beliefs about reality, about human knowledge, and about ethics, but also beliefs about how beliefs ought to be formed.
Atheist: Atheism is not a belief, but a lack of belief.
Christian: In what exactly is atheism a lack of belief?
Atheist: Atheism is a lack of belief in God.
Christian: Why does atheism lack belief in God?
Atheist: Atheism lacks belief in God because there isn’t evidence that God exists.
Christian: So Atheism believes that all beliefs should have evidence to support them.
Christian: Isn’t that a belief?
Atheist: Not really.
Christian: Of course it is. What evidence can you provide that demonstrates that all beliefs must have evidence to support them? Does “this belief” that all beliefs should have evidence to support them, have evidence to support it?
Atheist: It is self-evident.
Christian: How is it self-evident? A self-evident belief is one whose denial entails a self-contradiction. My denial that all beliefs require evidence to support them is in no way self-contradictory.
The claim that atheism is merely a lack of belief is demonstrably false. The claim that atheism makes no claims is a claim as well. I said that the claim that all beliefs should be supported by evidence is not self-evident. Now, let’s look at the opposite view. Here is an argument that you should think about:
Assertion –> Belief
This is the Modus Ponens form of the argument. Now, notice something very interesting. If you want to get to the conclusion of no beliefs, you have to deny assertions. What happens when you deny assertions? Think about it. Can you deny assertions without engaging in self-contradiction? Indeed, you cannot. This argument, taken transcendentally, is making the case that belief is the necessary condition of assertion. In order to deny assertion, one must deny belief. But we cannot deny belief without presupposing it. The claim is self-defeating because it entails contradiction. This means that we know that beliefs are the necessary condition of assertions because of the impossibility of the contrary. And the contrary is impossible because it involves contradiction. In other words it is impossible to assert non-belief about God without expressing some belief about God.
Assertion –> Belief
This is the Modus Tollens form of the argument. It says that belief is the necessary condition of assertion, but that there is no belief and therefore, no assertion. However, the argument cannot be made unless there is assertion and on the face of it, it is false because it entails self-contradiction. In other words, the conclusion of this argument is made impossible by the very existence of the argument. think about it this way, my assertion that there is no belief is impossible to assert since belief if the necessary condition of assertion. The argument is valid as far as form goes. But since the second premise false, the argument is unsound.
Is atheism a worldview? Indeed, it is. Is it true that atheism is merely a lack of belief about God’s existence? It is not since such a claim is self-contradictory. Is it the case that atheism makes no claims? It is not the case since the very proposition of “making no claims” is itself a claim. What Christians have to do is move slower in these encounters, think about what is being asserted, and ask what has to be true in order for the claim to be true. Atheists are atheists because they are unwilling to acknowledge God’s existence or admit that the evidence is all around us and within us, and that such evidence demonstrates God is there. God has made Himself known to all men. What men do with that knowledge and how they interpret that evidence is another matter altogether. But make no mistake about it, there is knowledge of God and there is evidence for such knowledge as well.
I have employed a transcendental argument to refute the atheistic claims that atheism is not a worldview, does not assert belief and makes no claims. If a transcendental argument is sound is conclusion cannot be denied without self-contradiction.
 See Ronney Mourad, Transcendetal Arguments and Justified Christian Belief (University Press of America).