Biblical?

Read this from a book called Sideways, by Rex Pickett:

"It was an inky, almost biblical, 100 percent Syrah with truckloads of ripe fruit..."

What does it mean by saying the wine was "biblical"?

I think it means its extraordinary quality: this Syrah was so good like it was in biblical times, when wine
"was a part of daily
life for the people of the Holy Land in biblical times, a
wine-producing and wine-consuming land".

Biblical would seem a strange way to describe wine.

I agree. And personally, I think a simple "all right" or "damn nasty" would cover most of them.

Biblical = mythical

alternatively, "inky, almost biblical" is talking about the colour, as refers to the plague of darkness in Egypt. Biblical usually refers to a dramatic weather change, or plague of some sort; eg "a plague of locusts of almost Biblical proportions"

so in this case the hint is in the reference to its inky colour. ie very very dark