Warlock: The Armageddon (1993) on Netflix

Plot summary

In the distant past, Druids held back the rise of Satan's son with rune stones, until Christians who believed their ritual was Satanic attacked them. Most of the Druids died and the stones were scattered. Now Kenny Travis and Samantha Ellison are in love and arguing, and both of their fathers are Druids: Samantha's father Ted is a priest who has neglected his duties, and Kenny's father Will is also of the order. Kenny is meant to become a Druid warrior and learns to use his powers, with Samantha at his side. A young woman, Amanda Sloan, wears a rune stone that has come down through her family, and during a lunar eclipse the Warlock, Satan's son, is born. Through Amanda, Satan tells the Warlock to gather the remaining rune stones within six days and summon him to Earth.