If you found a clock and examined the mechanism within it, you would probably think that this intricate mechanism was not the outcome of mere chance, that it had been designed.
Now look at the universe; is it possible that such an intricate mechanism, from the orbits of planets round the sun to the cells in your fingernails could all have happened by chance? Surely, this enormously complex mechanism has been designed, and the being that designed it must be God.
This is the design argument. I am not quite sure it is valid but what do you think?