So the ancient Hebrews, when they went into battle, they'd bring along the Ark of the Covenant. They figured God lived in there, and if they had God with them, they couldn't possibly lose, right?
Wrong.
If you read the Old Testament, you might get the idea Judea had this great military history, but frankly they were no match for the Babylonians, or the Persians, or the Egyptians, or the Greeks, or the Romans. But they kept going into battle with the Ark, and often as not, they'd get their butts kicked. Every once in a while, the opposing army captured the Ark, and according to the Bible, God would put a curse on them until they returned it, but more than likely, they were just like, "What's this piece of junk? Here, you can have it."
Around the time Babylon overran the place and took the whole bunch into captivity, it began to occur to people that maybe the Ark wasn't doing them much good after all, and most of the rest of the Bible is puzzling out the two questions: if God isn't in this box of ours, where is He? And if you can't put God in a box and have Him win battles for you, what's the point of having Him in the first place?
These days the concept of God in a Box has come back. Fundamentalists who deny any truth that isn't in the Bible believe they have God in a box. The name of the box is the Bible, and a handy portable box it is, too. People who preach the gospel of prosperity are basically pedaling God-in-a-Box Theology. With God at your side, you can't lose the (economic) battle. Saying God will make you rich, amounts to the same thing as saying He'll defeat the Hitites for you. If you can carry God around with you, He will conveniently clobber whomever you want clobbered.
On Easter Sunday, so says Luke, Mary goes to the tomb looking for Jesus. And boy, is she upset when the stone's rolled away. She figures someone must've stolen him. But she should have known. You can't keep God in a box.