A question: if strong-drink was only 15% alcohol and below in biblical times, how was it used as a starter fluid? I believe you need much stronger alcohol to light a fire, no?
From a recipe:
As soon as the mushrooms are colored add the marsala wine.
Caution: the Marsala wine is flammable so watch for spills.
The legal description of Marsala wine:
"Marsala" wine, over 14% vol. alcohol, in containers holding 2 liters or less
So it appears that at the high end (strong drink), naturally fermented beverages are flammable. I don't know without additional research exactly when a flashpoint is reached.