Some hedonist who felt that sometime or another, the majesty of the Roman Catholic Church was just too much, and this was their idea of a very evil prank.
Of course, the pranksters could have simply set fire to the church, too.
Nothing is really beyond repair or replacement. This was just malicious mischief. The mission of the church is unchanged in any way.
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You are right.
The tabernacle was just a thing, an object. It wasn't a LIFE. It can be replaced.
He may not even have been thinking of "the majesty of the Roman Catholic Church" either. He might have thought to steal and sell for drugs. Who knows what that creep sad soul was thinking. Perhaps "thinking" wasn't his strong point.