After debating theology for a long time, an argument that constantly comes up for the existence of a deity is that, if one were to look at a painting, one would clearly know that the painting had a creator, regardless of whether or not they've actually met the painter or watched the painting get made, and that such things are comparable to the universe. This is often called the “Watchmaker Argument”, because the painting in question is usually substituted for a watch.
There are a few problems with this argument—one being that we can trace the watch or the painting back to its creator, due to a sign that is often connected with its creator; for example: an artist's signature on a painting, or a creator's logo/signature engraved on the watch. We cannot trace the universe back to a creator because we do not know if it has even has a creator.
Another reason why we can tell that a painting or a watch has a creator is because we can compare it to other objects of the same category. We know a watch or painting must have a creator, because we've observed such things be created, but have never observed such things form in nature or without a creator. We have not observed other universes, if there be any. Because of this, we cannot compare the universe to anything, because there is nothing on a large enough scale to compare the universe to, and to determine reasons to explain its behavior in full.
The big (if not only) reason why we know how watches, paintings, and other such objects behave is because we are the inventors of such things; we know the behavior of these objects because we designed them to behave in that certain way. On the other hand, humans were not the creators of the universe, but are merely just subjects of it, therefore we are not entirely sure how it works.
This entire “watchmaker”/“painter” analogy fails, because it compares apples to oranges. The only similarities these artificial objects share with the universe are in irrelevant details and how we humans perceive and react to them. Any other comparison that does not fall into those two categories is a stretch of truth.
