The quotation below is from a post, "The Improbability of Chance", by Joe Carter on the Evangelical Outpost blog:
"One of the arguments for creation is something like this: 'Look at the amount of complexity in the human and natural world. The probability of something this complicated happening by random chance is [insert fantastically small number here]. Therefore, it is rational to conclude that life did not occur by chance, but rather by design....'"
"There are 55 parameters that are necessary for human life to develop on a planet. These elements consist of such parameters as the size of our galaxy to the carbon dioxide levels in the atmosphere. To complicate matters, each parameter has a very limited range. For example, if the age of our planet was too young it would rotate too slowly to sustain life; any older and it would rotate to rapidly. Like the porridge in the tale of Goldilocks, the universe has to be “just right” in order for humans to exist.
"While the universe could have developed in an almost infinite number of ways, the requirements for human life are much more limited. Therefore we can measure the probability of all 55 of these parameters falling in the range of “just right.” The possibility that one planet like ours would meet all of these conditions is less than 1 in one hundred billion trillion trillion trillion. I don’t know about you, but I consider that a fairly “low probability.”
Hugh Ross, discusses this subject in more detail in his article, Design Evidences in the Cosmos. Dr. Ross lists thirty-four parameters of the universe that must be carefully fixed in value for any kind of conceivable life (not just life as we know it) to exist at any time in the history of the universe. He lists an additional sixty-six parameters that must exist in the sun and the earth.