"Christianity: Why do some Christians and other theists lean so heavily on the origin of the universe ("creation") as proof of the existence of their deity, rather than evidence if the deity's presence in the world today?"
I answered, and decided to post the answer here as well. So, here ye go. :-)
*nod to Barry - thanks for the invite.
The answer to this question has a number of levels, which are worth considering, but cultural pressure has got to be considered at the top of the reasons for this tendency.
The argument against the existence for God (or gods) based upon evolution and random occurrence as the sources for the origin of the universe has been one of the primary debate points by atheists and skeptics since shortly after Darwin's introduction of evolutionary theory on November 24, 1859.
It can only be expected that this argument against the existence for God would be countered by theists of all kinds. A general theory arguing against the existence of any personal (or impersonal) deity based upon a theory of origin is an argument against all deities.
It has only been 154 years since the initiation of this issue as a primary argument against the personal interaction of a god has been rolling around in our culture. 154 years is not a long time for the development of a major paradigm shift. The imprecise nature of measuring time in billions of years, and tracking evolutionary change we can not observe with our eyes makes this paradigmatic transition a slow and awkward one.
The question, of course, can be reversed. Why do atheists and other skeptics insist on using the origin of the universe as an argument against the existence of God(s)? The cart may be in front of the horse with this question.
Historic events in America (such as the Scopes trial) have made this an even hotter topic than in other countries. It is not even 100 years since that event. People are still alive today who can mark that trial as a evental moment in their lives.
Believers in the existence of a deity can not be expected to argue for a deity they do not believe in. Thus, their arguments will typically come from the perspective of their own faith system.
The words "proof of the existence of their deity" are underlined. I am assuming this is a significant sub-point to the question. One can not expect a person of faith to argue for something they do not believe. Thus, I would not argue for the existence of the Mormon deities, Allah, or Krishna and the pantheon of Hindu gods and goddesses. Yet, I will submit that arguing generally for the existence of deity in general may be more effective than arguing for a specific deity in this particular debate.
Many people still believe that variations on William Paley's watchmaker illustration is as effective as when it was introduced in 1802.
The teleological argument for the existence of God is still alive and well. Oxford mathematician John Lennox, and Philosopher William Lane Craig are just two examples of scholars pressing the teleological argument today. Craig has revived the Kalam Cosmological Argument. Because brilliant people still hold variations on the teleological argument as valid, one can not consider the argument dead. To do so may be proof of a bias.
William Lane Craig
Kalām cosmological argument
The debate appears to be at a stalemate. Because of this, when a debate on origins is presented to the public it looks like two heavy weight contenders fighting for an unclaimed title belt.
Each side thinks that they are the winner and the debate has been won by their side. Ultimately no significant change appears to happen, but it sure sells books as the debate keeps going. So, perhaps each one of us who has bought a book, watched a debate about this subject, or had our own debate about it as responsible for the ongoing passion concerning the topic.
Is that bad? That's for the individual to decide, but if it was to become my passion, what is that to you? ;-)
This stalemate does look ridiculous to many people. Micro-biologist John Shapiro referenced this stalemate back in 1997 in direct response to books by Dennet, and Dawkins.
"Both sides appear to have a common interest in presenting a static view of the scientific enterprise. This is to be expected from the Creationists, who naturally refuse to recognize science's remarkable record of making more and more seemingly miraculous aspects of our world comprehensible to our understanding and accessible to our technology. But the neo-Darwinian advocates claim to be scientists, and we can legitimately expect of them a more open spirit of inquiry. Instead, they assume a defensive posture of outraged orthodoxy and assert an unassailable claim to truth, which only serves to validate the Creationists' criticism that Darwinism has become more of a faith than a science."
Is Darwin in the Details? A Debate
James A. Shapiro
As far as evidence of deity in the world today: If you think the teleological argument is a rough one to follow try bringing up the active presence of God as a debate topic.
Each time I see this one come up, it seems to get personal. ;-)