The argument for god often comes in the form of an appeal to complexity. Usually a theist will reference the complexity of the cell and it multitude of functions, The intricacy of DNA or the "fine tuning" of the universe when making their case for the existence of god. But doesn't complexity make a better case against the existence of a "designer" or a god?
If we think about what "god" would ultimately be, It would be an entity that created everything. He devised the laws of the universe, He decided what our tolerance to radiation should be, How much water we need to drink. He would be consciously responsible for everything, Every last aspect of every system would be made by him. There is no law, No force, No energy, No substance and no part of any organism that wouldn't be consciously devised.
If that is the case and we assume god can do anything, Why make things so complex? Simplicity would be the best route and god should be able to make things infinitely simple. Why have cells, or even atoms.
If god was in charge of everything why not make the cell as Darwin and his contemporaries envisioned it. A blob of goo. If god is capable of doing anything why is the cell so complex and prone to failure when it could be a simple blob of goo? In fact, Forget the cell, If god can do anything why are animals and plants not just one animated conscious blob of goo, Why do we have so many intricate components when god could have made it so simple?
To me the answer is simple. The cell, And humans, have evolved to function in a set environment. The universe appeared, laws were set and now it's up to organisms and cells to evolve to work within those laws. No god was involved at any point, because if he was, Everything would be a lot simpler.