Mortals get tried in absentia, so it's not entirely unprecedented to get a judgement that you can't currently enforce.
Also, getting enough evidence to actually secure a conviction would imply quite a lot of new facts discovered compared to now; perhaps along the way we'd find out something useful for sentencing, too.
We could start by putting the devil on trial and getting god to give us information about how to imprison supernatural entities...
Mortals get tried in absentia, so it's not entirely unprecedented to get a judgement that you can't currently enforce.
Also, getting enough evidence to actually secure a conviction would imply quite a lot of new facts discovered compared to now; perhaps along the way we'd find out something useful for sentencing, too.
We could start by putting the devil on trial and getting god to give us information about how to imprison supernatural entities...