God did it
The phrase God did it summarizes a large number of answers offered by monotheistic religion (especially Christianity) as alternatives to scientific explanations. As an answer, it is a fake explanation, a curiosity stopper, and problematic in a number of other ways as well.
Kicking the Can
If you invoke God to explain where the universe (or the earth, or life, or people) came from, this opens the question of where God came from. Surely God must be at least as complicated and amazing a creation as that which God supposedly created -- i.e. the universe, with all its stars, planets (including Earth), life, and intelligent life.
If "a creation implies a creator", then who or what created that creator? "God did it" just kicks the explanatory can over to an even more complicated question. This violates the Occam's Razor principle of explanation, i.e. that the simplest explanation which fits the known evidence is the best one to start with.
- How did God do it?
- How do we know (or why do we believe) that God did it?
- Why did God do it? (This question is typically answered with another fake explanation, "God works in mysterious ways."
- How does God work, anyway?
- How do we know that God didn't "do it" using methods (or leaving evidence) discoverable by science, and that the scientific explanation is therefore correct?
- Why do we believe that God did it if we have evidence of a more believable explanation?
Invoking God to explain anything is essentially giving up the search for a rational or useful explanation – because God can be used to explain anything, with no intellectual work required. "Why is the sky blue? Because God made it that way! Why did my computer crash? God made it happen! Why won't my car start? Because God willed it not to start! Where did the Earth come from? God made it!" Rational study of the available evidence has revealed or can reveal answers that are useful in the sense of giving us more control over the reality around us. "God did it" does not give us any more control or understanding of how the world works.
The answer "God did it" stops curiosity because the obvious follow-up questions (see above) all fall into areas into which religion strongly discourages inquiry -- even if objective inquiry were possible, since no reliable method is known of detecting "God" (indeed, theists often use the idea that God is undetectable as a counter to arguments against the existence of God).
As an answer, it is equivalent to saying "that involves things which nobody was meant to understand" -- an idea sharply antithetical to curiosity and the spirit of scientific investigation.
If we presume that the world was actually created by God in the space of a week some 6,000 years ago, including all the fossil beds and geological layers and galaxies of various apparent ages (and countless other bits of evidence that the universe is well over a million times older than this), then why is it not just as reasonable to presume that everything was created in 1957? Or last Thursday [W]?