From this website, which provides a lot of detail on the AD 79 eruption:
The few Roman depictions of Vesuvius on wall murals all show the volcano as a single cone with no hint of Monte Somma. In addition, medieval and Renaissance depictions of eruptions invariably show the summit of Vesuvius below the summit of Monte Somma instead of substantially above it as it is today.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.