When a negate all is interrupted, only the ongoing prevent part of the negate all reactivates. So the ignore works.
The problem in this example is that Midianite Attack is the last card played and it was played by your opponent. That's a separate item of the 3 things that "Interrupt the battle" interrupts:
1. All ongoing abilities in battle
2. Any abilities in battle causing special initiative
3. The last card played in battle, if it was played by your opponent
Midianite Attack's ongoing Prevent ability falls under category 1, but the whole enhancement falls under category 3. So I think Midianite Attack's whole ability would be interrupted, including the instant Negate ability.
Seems to me that Midianite Attack would reactivate and Negate Faith of Moses' Parents?