The spirituality of Saint Montfort became a way for Montfortans to draw closer to Jesus Christ and live out their vocation. But it was not only the  Montfortian who live it, many lay people also draw enthusiasm and spirituality.

Saint Montfort has indeed died, but his followers such as Father Adrien Vetel, Father René Mulot, and Brother Mathurin up to the next generation continued the work and spirituality of Saint Montfort. What is Saint Montfort's Spirituality? Montfort or Montfortan Spirituality is the Spirituality of the Cross and Marian. It can be seen simply in the logo: DS, AM (DS=Deo Soli, AM=Ave Maria). Deo Soli (Only God) shows the totality of the Montfortans to surrender themselves to God like the totality of Christ's surrender (emptying) of himself to humans in the events of the Incarnation and the Cross. Ave Maria (AM) shows the Marian dimension in living out their surrender to God. Mary is the model for Deo Soli. People cannot surrender themselves totally to God (Deo Soli) without Marian values living in their hearts. Therefore, Saint Montfort's spirituality is the Spirituality of SELF-DEVOTION to Jesus through Mary. Montfort starts from his thesis that “through Mary Jesus came into the world and through Mary he must reign in the world” (TD 1). Reigning in the world means becoming more united and similar to Christ. This unity and similarity only occur in and through Mary. Because, if Jesus took on human form in Mary’s womb (kenosis in the incarnation), then in turn the same womb becomes the place of formation of the human self to become divine (theosis in devotion). Kenosis is the process of “descending” while theosis is the process of “ascending”. In both the processes of “descending” and “ascending”, Mary remains the template for the process of transformation: becoming human from God’s side and becoming divine from man’s side. This is why Montfort says “if the head of humanity, Jesus Christ, was born of Mary, then it follows that the elect who are members of that head, were also born of this woman. It is impossible for the same mother to give birth to a head without members, nor is it possible for members to be without a head (TD 32)”. This is God's will, because Montfort says, "God the Father wants to create his children through Mary until the end of time" (TD 34). In fact, Montfort is talking here about Mary's spiritual motherhood, namely that Mary personally and completely involves herself in her motherhood, cooperating with the Three Divine Persons in order to regenerate us into the likeness of Christ.

For Montfort SELF-DEVOTION to Jesus through Mary is the perfect form of renewal of baptismal promises. Montfort's logic was simple, that almost all Christians betrayed the loyalty they had promised to Jesus at baptism. Where did this chaos come from – says Montfort – if not because people forgot to live up to the promises and commitments of holy baptism (TD 127-130). So, for Montfort, just like the Council of Trent and the Church Fathers said that the best way to treat this disease of forgetfulness is to renew the baptismal vows. For “we carry this treasure (the grace poured out in baptism), which is more precious than heaven and earth in a fragile vessel” (TD 87). And the perfect renewal of the baptismal promises only occurs in SELF-DEVOTION to Jesus through Mary. Because, we carry out this devotion personally, voluntarily and with full awareness rather than when we are baptized where sometimes the promise is conveyed through the mouths of other people (parents, godparents, etc.). In terms of formulation, there are four formulations of SELF-DEVOTION written by Montfort and one of the formulations is used in the Legion promise. The question is, why is the renewal now "through Mary". The answer is clear, it is because Mary is someone who has achieved her goal precisely because she faithfully lived out her calling. its fundamentals. So, she will teach the faithful how to reaffirm and live out the YES that was once said at baptism. Here the renewal of baptismal promises is the same as the renewal of commitment to be in a new way in Christ. To be in a new way in Christ, Mary becomes a kind of filter which filters every action of our life of faith. The more Marial a person is, the more he or she is like Jesus Christ and this is the true meaning of our baptism: to become wholly Jesus's (Totus Tuus – says Montfort).

Saint John Paul II was so convinced of this Montforte spirituality that in his Encyclical Redemptoris Mater the pope wrote that “among the many witnesses and teachers of Marian spirituality, we recall Saint Louis-Marie Grignion de Montfort who proposed consecration to Christ through the hands of Mary as a powerful means for Christians to live their baptismal promises faithfully” (SM, No. 48). And again the pope, whose motto Totus Tuus is taken from Montfort’s writings, said that “Grignion de Montfort leads us into the heart of the mysteries in which our faith lives, grows and bears fruit” – and by that he meant the renewal of baptism.