The cosmological argument is one of the most common arguments for God's existence, but it is obviously flawed in at least three ways:

1. If everything must have a cause, then so must the supposed First Cause, that usually is styled 'God' (and normally without further argument also declared to be benevolent, infinite, all-knowing, and all-powerful). And if not everything must have a cause, the whole argument fails to start, and indeed the universe may exist accidentally.

Note what the logical difficulty here is: If everything must have a cause, it does not follow that there must be a first cause, but that there cannot be a first cause, for it then too must have a cause.

So it seems more sensible to infer that, first, not everything must have a cause, and second, while there is excellent reason to assume there is one natural reality of which everything that exists is a part, there is no good reason to assume more than that, such as divinities, angels, devils etc., for which there is little evidence that they exist, and much evidence that at least most of these supposed entities are merely fantastic, and based on fear, ignorance or wishful thinking.

2. In a somewhat different style, but to similar effect, it is often argued that everything (made) must have a maker, or designer, or else it could and would not exist. This assumption has a similar flaw: If everything must have a maker or designer, the first maker or designer must also have a maker, and we proceed again to an infinite list of makers of makers of makers of ... Hence, as with the first argument, it makes much more sense not to start that infinite regress by assuming that there must be a maker of what exists. (See: Design argument).

3. Finally, there are two objections to the move that is often made to save the introduction of a First Cause of all, namely (a) that there must be an origin or beginning to a sequence of causes (e.g. for it to have started or be possible at all) and (b) that the First Cause is so perfect (or peculiar, or special, or powerful) that it, unlike everything else it caused, it is not itself in need of any cause.

The answer to (a) is that this merely begs the question, and that there seems to be no logical objection whatsoever to an infinity of times in the past or the future in which there always was something, possibly complicated by chance to make things happen.

The answer to (b) is that again it begs the question and makes an assumption that contradicts the notion that everything must have a cause distinct from itself, that is at bottom of the Cosmological argument. And furthermore, since God's existence is speculative but Nature's existence is taken for granted, it seems much more simple to assume that if there is a First Cause that always existed, it is nature rather than something that made nature - which has the additional logical shortcoming that it assumes far more than needs to be assumed to start with.