There is an argument against creationism that some time ago occurred to me and, as you have publicly demonstrated your willingness to discuss such matters maturely, I would be honoured to read your opinion of it. It is not an argument that I claim to be of great depth or sophistication, but a simple point to consider.

A number of theists have asserted that the best explanation they have found for the immense complexity of life and the universe is that of intelligent design. To my mind this explanation has a central, fatal flaw: If intelligence was required to create the universe and intelligent life, how might we explain the existence of the creative intelligence of god?

Other than blind faith, or the logical paradox that god would have created himself, how do you suppose a theist might respond? I have not yet found polite opportunity to present this point to a theist myself, but hope that you may provide some insight based on your experience of conversation with them. Apart from that, as stated earlier, I would be honoured to know your opinion of the argument's validity.

Whether you know it or not, this is a big, gigantic question with many facets that are worth exploring. I'll go over a few of the biggies briefly, and see if that helps.

First, if someone says that, to them, they can't comprehend how the universe could have come into existence without a creator, then they are just making a statement about their personal understanding of the universe. That's okay. If someone says, "I am not convinced" about some subject, you can't retort with "Yes you are" because they are making a personal statement about themselves, and you can't argue against such a statement. You might introduce them to more evidence and hope that they change their mind, but if all the evidence in the world wouldn't convince them, then you're stuck.

The important thing to remember, though, is that the person who believes in God because they can't conceive of a universe that was not created can't be argued out of their feelings, but they also can't use those feelings to draw conclusions. For example, I couldn't say, "I can't conceive of a universe without a creator, therefore there must be a creator, therefore the Christian God exists, therefore if you don't believe in Jesus you are going to Hell." That doesn't follow. The most this person can say is that they are convinced that there must be a creator. Any attributes assigned to the creator (such as that it is identical to the Christian concept of God) are subject to debate.

Second, most people who talk about intelligent design aren't talking about just the origin of the universe -- they're talking about life on the planet Earth. That's a very different subject because it is heavily susceptible to scientific inquiry. If a person believes that God has a hand in the creation of life, it seems to me that they must be either, a) be Biblical literalists who either seriously misunderstand the evidence or assume it's false, b) believe that evolution is limited to change within species and that all species were created by God (again forcing them to ignore or dismiss copious evidence unless they think that species were created over time and not all at once), or c) believe that God works through physical laws without violating them (as Catholics believe). The first two options are pretty easy to argue against. The third option you can't disprove, but it also is not necessary from a scientific point of view.

Third, there are many arguments for why the statement "everything must have a cause" (itself debatable) does not apply to God. Like you, I don't buy them. Most of them boil down to a statement that God exists because God necessarily exists, and many of those are pretty much just linguistic arguments or logical tricks and therefore not compelling. To me, if something has to have existed back into infinity, then the universe (or a series of universes) seems much more likely than any sort of deity.

The most interesting thing about this type of question is that not all theists answer in the same way. Some will have answers that they've learned to parrot (and that they don't expect you to be able to respond to), some won't have an answer (but be comfortable just having faith), and some will be amazed that you would even ask.

I hope this help answer your question. Let me know if you'd like to discuss any aspect of this further.