In Roman Catholicism, the fleur-de-lis is a significant symbol representing the Virgin Mary, embodying her purity, divine motherhood, and unique relationship with the Holy Trinity.
Its immaculate whiteness symbolizes Mary's purity and virginity, a central tenet of her veneration.
The three petals of the fleur-de-lis are widely interpreted as representing the Holy Trinity—God the Father, the Son, and the Holy Spirit—while the band or bracket at the base of the symbol is understood to represent Mary herself.
This interpretation highlights Mary's essential role as the one who bore the Son, a tradition stating that one cannot fully understand the Trinity without acknowledging her.
She is seen as the "daughter of the Father, mother of the Son, and spouse of the Holy Spirit," a concept affirmed by the Second Vatican Council.
The symbol is also linked to the "lily among thorns" from the Song of Solomon, a scriptural reference interpreted as a metaphor for Mary's purity amidst a sinful world.
Furthermore, the fleur-de-lis symbolizes Mary's royal status as Queen of Heaven and her role as a model of faith, hope, charity, and justice.
The symbol's adoption by the Church, including its use on banners during the coronation of Charlemagne by Pope Leo III in 800 CE, underscores its deep connection to both ecclesiastical authority and Marian devotion.