As one great Furnace flam'd, yet from those flames No light, but rather darkness visible.(Milton, Paradise Lost)
By faith he left Egypt, not being afraid of the anger of the king, for he endured as seeing him who is invisible.(Hebrews 11:27)
"Where's God?" That's a common complaint, by believers and unbelievers alike.
One time, as I was returning from a walk, it was getting dark. The street lights were on. Cars in the oncoming lane had their headlights on. And I could see cars with glowing taillights in the other lane.
I was on the sidewalk when, a block or so ahead of me, a minivan pulled out of a parking lot and made a right turn onto the road. Only he didn't have his lights on.
I dimly saw the side of his van, but once he straightened out, he was essentially invisible. I couldn't see the back of the unlit van in the darkness.
But here's a paradox: I knew he was there because I couldn't see him! At first blush that doesn't seem to make a lick of sense. Yet I knew he was there because of what I couldn't see. When he pulled out onto the road, he blocked my view of cars of ahead of him. If he hadn't been there, I'd be able to see the last car in line from the glowing taillights. But his car obscured the view, like a black spot where there ought to be light. Like a black spot encircled by light. I knew he was there due to the contrast between what I could and couldn't see.
By the same token, God can be active when he seems to be inactive. God can be blocking evil, only we can't see it because his intervention renders his intervention indetectable. If God preempts an evil, then there's no record of that nonevent. If God prevents an evil, that preemptive action leaves no trace behind–for the evil never happened.