The celebration of February 15 is tied to the ancient Roman fertility festival known as the Lupercalia, honoring the god Lupercus. This festival, centered at the cave of the Lupercal on Rome's Palatine Hill, was deeply significant to the Romans, considered one of their oldest and most important festivals. Rituals during the Lupercalia included young priests running nearly naked around the old city walls, striking bystanders with thongs from sacrificed animals to cure sterility, and a purification ceremony for Roman women by the priests of Pan Lyceus. The Lupercalia survived into the Christian era until AD 494, when Pope Gelasius I transformed it into the feast of the Purification, initially observed on February 14 before being moved to February 2. The historical practices of February 15 reveal a pagan origin that God's people are cautioned to avoid, focusing instead on His commanded holy days.

According to tradition, Nimrod's mother presented herself for purification on February 15, forty days after his believed birth date of January 6. On this date, pagan Rome celebrated a sensuous festival of idolatrous worship beginning the evening before on February 14, in honor of Lupercus, the deified hero-hunter of wolves, known as the Lupercalia. This festival encouraged young people to indulge in licentious acts of sexual immorality. In AD 496, Pope Gelasius officially Christianized the pagan Lupercalia by renaming it Saint Valentine's Day and moving the day of observance from February 15 to February 14. Roman church members were then to center their attention on Christian saints, drawing lots with saints' names instead of engaging in the original pagan practices.

Centuries before the birth of Christ, pagan Rome celebrated February 15, beginning the evening before on February 14, as a sensuous festival in honor of the idolatrous worship of Lupercus, the deified hero-hunter of wolves. This ancient Roman practice especially encouraged young people who were attracted to each other to indulge in licentious acts of sexual immorality. After the sacrifice of goats and a dog, the priests, called Luperci, traditionally ran a marked course around the city on this day, scantily dressed only in goatskin girdles and carrying strips of goat skin with which they struck women to take away their infertility. The strips bore the name februa, a word connected with februare, meaning to purify, and thus the day was called Februatus, and the month, Februarius. Lupercalia was connected with the legendary she-wolf who suckled Remus and Romulus, the traditional founders of Rome, and the term wolf became a synonym for a sexually available woman, linking the day to Venus, goddess of sexual love. According to secular history, Nimrod, known as the mighty hunter before the Lord, was believed to have been born on January 6, with his mother presenting herself for purification 40 days later on February 15. In AD 496, Pope Gelasius officially Christianized the pagan Lupercalia by renaming it St. Valentine's Day and moving the day of observance from February 15 to February 14.