I’m an atheist, so my position on God’s existence is based on the premise that the arguments for God’s existence fail.
I can’t go through every argument in an internet post, obviously, but I will list a few sample arguments and explain why I reject each of them.
The Kalam Cosmological Argument
1. Whatever begins to exist has a cause.
2. The universe began to exist.
3. Therefore, the universe has a cause.
This argument is based on an equivocation between different arrangements of matter and matter itself. We have sufficient evidence that every arrangement of matter has to have a cause, but no evidence that matter itself requires a cause. Actually, the first premise implies that the universe is eternal, interpreted properly, since every arrangement of matter would need to have a cause in a prior arrangement of matter, all the way back forever.
In addition, this argument does not establish that the cause would have to be God. Craig attempts to give a conceptual analysis of the cause of the universe, but it is very weak, especially the principle of determination that he uses to justify the inference to a conscious cause.
The Fine Tuning Argument
This argument attempts to support the claim that God exists using the alleged fine tuning of the constants of the universe. These constants had to be within incredibly small, specific ranges to allow life to emerge. This fine tuning is very unlikely given naturalism, but it is at least not incredibly unlikely if God exists. Therefore, the fine tuning is evidence for God. (Robin Collins is an example of a theist who uses this argument.)
The problem with this argument is that none of the premises can be objectively supported. It’s controversial among physicists whether the fine tuning even exists. It isn’t clear in what sense the constants of the universe might have been different from what they are or how we could objectively determine the “probability” of their being at the values they are, either.
Finally, we have no basis for the crucial premises about what is likely given naturalism and theism. Who is to say that this sort of fine tuning is unlikely given naturalism – on what basis? Further, how could we objectively predict what God would be likely to create, given that our human preferences and values do not necessarily track the preferences and values that God would have? The fine tuning argument’s claims about God are based on nothing more than unjustified anthropomorphism.
The Argument from Miracles
The argument from miracles attempts to establish that God exists on the basis of miracles that allegedly occurred. One alleged miracle that is popular among apologists, and crucial for the Christian religion, is the alleged miracle of Christ’s resurrection. The textual evidence in the Bible, particularly the Gospels, is alleged to contain enough evidence to establish the claim that Jesus rose from the dead.
The problem with any argument from miracles is that there cannot be sufficient evidence for an event that violates the laws of nature. A law of nature is supported by countless observations over the course of human history, so we cannot allow one event, which is only supported by ancient texts of dubious reliability, to overturn it. Our experience uniformly shows that people who die stay dead, and we cannot allow the Gospels, which were written by fanatics, to overturn such a strong generalization.
Sometimes apologists say that the credibility of miracles depends on establishing the existence of God first, but this only shows that miracles cannot be evidence for God’s existence, since they presuppose it. If we have to believe in God to believe in miracles, then we cannot use miracles as evidence that God exists on pain of circular reasoning.
In conclusion, the case for God’s existence is very weak indeed.
Note: I copied and pasted this post from an internet forum post that I made elsewhere.