of biblical proportions

Reader's Digest 6月号の記事 'RESCUE DOG' から引用します。
When he heard me, he swam to shore, ran out of the water, beelined right to me, and launched into a reverberating full-body shake of biblical proportions. He completely drenched me with mud and pond water, and not for one second did it make me angry.
"biblical" では聖書の事しか連想できないので "biblical proportions" の意味が分かりません。辞書を見ます。

・Oxford English Dictionary: Very great; on a very large scale.: We need rainfall of biblical proportions to bring us back to normal.

・Collins Dictionary: Very great; especially, exceeding previous records in scale.: of biblical proportions; with biblical fury

・Urban Dictionary: This refers to something which happens on the grandest scale possible on earth. This includes apocalypse, major war etc.: We cannot allow you to continue research on this weapon, it would cause a disaster of biblical proportions.
この意味での "biblical" は通常 "of biblical proportions" という慣用句的な使い方をする様です。