Private revelation can neither add to nor detract from the Church’s deposit of faith. Therefore, the Brown Scapular of Our Lady of Mount Carmel echoes the promise of Divine Revelation: The one who holds out to the end is the one who will see salvation (Matthew 24:13), and Remain faithful unto death and I will give you the crown of life (Revelation 2:10). The Brown Scapular of Our Lady of Mount Carmel is a reminder to its wearers of the saving grace which Christ gained upon the cross for all: All you who have been baptized into Christ have clothed yourselves in him (Galatians 3:27). There is no salvation for anyone other than that won by Christ. The Sacraments mediate this saving grace to the faithful. The sacramentals, including the scapular, do not mediate this saving grace but prepare us to receive grace and dispose us to cooperate with it. As the Catechism of the Catholic Church teaches:
Sacramentals do not confer the grace of the Holy Spirit in the way that the sacraments do, but by the Church’s prayer they prepare us to receive grace and dispose us to cooperate with it. For well-disposed members of the faithful, the liturgy of the sacraments and sacramentals sanctifies almost every event of their lives with the divine grace which flows form the Paschal mystery of the Passion, Death, and Resurrection of Christ. From this source all sacraments and sacramentals draw their power. (CC 1670)
We see, therefore, that the Church clearly teaches that all grace, including that of final perseverance, is won for us by the Passion, Death and Resurrection of the Lord. Simply wearing the Brown Scapular does not confer that same result.