It is said that Intelligent Design is unfalsifiable.
Au contraire. It is eminently falsifiable. All that the unguided evolutionists need do is give a reasonably detailed explanation of how something like the bacterial flagellum came into being, taking proper account of probabilities informed by experimentally established physical reality and not glossing over important details or difficulties.
ID would then be falsified for all intents and purposes.
If the unguided evolutionists can do this, then ID is falsifiable. But if they cannot do this (or refuse to do this), then the question becomes: Is unguided evolution itself falsifiable?
To maintain that ID is unfalsifiable would be essentially to maintain that unguided evolution is unfalsifiable.
The burden of proof is on those who claim that they have an explanation in terms of unguided causes for those complicated things that look designed (such as the flagellum). They're supposed to be the geniuses with the better explanation than the obvious (and allegedly way too easy): "Someone made this." They are supposed to be the heroes of Science! who are bravely willing to bear the burden of proof. If they can't explain something so basic as the flagellum, then what have they got, really?
We're all waiting to be impressed.