Doesn’t everyone hate the cosmological argument? Amiright? (My attempt at humor) But in all seriousness I find this argument to not only be stupid, but also waste of time to refute. Nevertheless, seeing as I do in fact have time to waste, I shall refute it.
The cosmological argument goes something like this:
- Things exist.
- It is possible for those things to not exist.
- Whatever has the possibility of non existence, yet exists, has been caused to exist.
- Something cannot bring itself into existence, since it must exist to bring itself into existence, which is illogical.
- There cannot be an infinite number of causes to bring something into existence.
- An infinite regression of causes ultimately has no initial cause, which means there is no cause of existence.
- Since the universe exists, it must have a cause.
- Therefore, there must be an uncaused cause of all things.
- The uncaused cause must be God. 
Fist off let me state that this form of the argument is found on the Christian Apologetics and Research Ministry. This is “legit” if you will.
Point 1: Things exist. I agree. This claim is all good.
Point 2: It is possible for these things not to exist. ehhhhhh one could disagree and there would be perfectly valid arguments against this but I will give our friend Matt Slick (the author of the page on CARM) the benefit of the doubt and agree. This one is fine.
Point 3: Whatever has the possibility of non existence, yet exists, has been caused to exist. Now this is what I take offence to. This statement is down right false. Things that begin to exist often do have a cause but that doesn’t mean they all do. Take fluctuations on the quantum level for example. Quantum fluctuations are completely random, uncaused events.“…Uncaused, random quantum fluctuations in a flat, empty, featureless spacetime can produce local regions with positive or negative curvature. …” ~~Victor Stenger 
Keeping this in mind we can see that the assertion that what begins to exist must have a cause is not only false but is down right deceitful. Uncaused events happen all the time and thus the main premise of this argument falls.
Point 4: There cannot be an infinite number of causes to bring something into existence. This is a fair assertion.
Point 5: Therefore there must be an uncaused cause of all things. Yes, that uncaused cause is either the universe bring itself into existence (in a way) which is not illogical because before time there is no cause and effect thus the universe can arise by itself, (I refer you to my previous post called The God before time? Why not the universe before time? ) or quantum fluctuations can be the uncaused cause. But let’s see what the final assertion that is made is…..
Point 6: The uncaused cause must be God! ……… really? I beg to differ. As suggested by the post above as well as the fact that quantum fluctuations can create a universe, why are we asserting that god is the uncaused cause?
“Once our minds accept the mutability of matter and the new idea of the vacuum, we can speculate on the origin of the biggest thing we know—the universe. Maybe the universe itself sprang into existence out of nothingness—a gigantic vacuum fluctuation which we know today as the big bang. Remarkably, the laws of modern physics allow for this possibility.” ~~Pagels 
Thus we can see that our current, highly successful model of the universe allows matter to be created from nothing, uncaused without invoking god as well as the fact that there is good evidence to suggest that our universe could be a fluctuation one can see that this argument falls.
In conclusion, the main assumption that this argument rests on is provably false and to be honest, I don’t understand why people still use it.
Further reading and footnotes: