What does this theory predict, how can those predictions be tested and what hypothetical observation would falsify the theory?
At the heart of design science is the notion of irreducible complexity. Prediction-- take a biological structure, remove a component and it will fail to function. Test--I will leave the technical problem of testing to someone better prepared than I am. Falsifying Observation--the structure would continue to function without the component.
How's that for short notice.
This comes from the old squabble that so much of science, especially biology, is reductionist in nature (everything can be reduced to physical and chemical mechanisms). Even some famous atheists have argued that not everything can be reduced (i.e. Ayn Rand who considered consciousness irreducible). So if something cannot be reduced (insert a leap of faith here) its complexity must be by design.
BTW the existence or non existence of God is not a scientific dispute since science deals with only concrete, observable and verifiable facts, not acts of faith. This discussion properly belongs in the field of Philosophy.