Although I can see how you might reason your way to such a statement, it is not logically supportable. The existence of God is not a logical prerequisite for theories stating that "Intelligent Design" is responsible for at least some of what we can observe of life on Earth.
If you're honest, you'll see that your statement relies on seceral Very Big Assumptions, including the following:
1. There is no life in the universe, except on Earth. (Otherwise, you'd admit the possibility that species from other planets could have played a role in creating life on Earth)
2. Intelligent Design and Evolution are mutually exclusive processes (this is a poor assumption -- a theory of "assisted evolution" easily combines the two, and helps to explain the fossil record)
3. God is the only possible intelligent designer (provably false: humans have demonstrated the ability to do it)
I think what you're really aiming at here is a global statement about the origin of life in the universe -- and you're claiming it sprang up randomly, and not through the actions of God. But you cannot apply such a theory to life on Earth.
" But you cannot apply such a theory to life on Earth."
Your post makes valid points, but ultimately ID & Creationism both rely on a 'God' (an Intelligent Designer). To date, proving the existence of such a super being is impossible. Thus, unprovable.
Personally, I tend to lean in the 'assisted evolution' direction.
I wish that more anti-evolutionaries would forgo all vaccinations and other medical responses to the rapidly-evolving flu viruses, etc that pop up each year.