The Holy Mass is the central act of Catholic worship. It was first celebrated by our Lord in its primitive form, and has continued to develop along with the Church as she continued to define the Faith, given to us by Christ, more clearly. As such, it is not surprising that the liturgical actions, gestures, and prayers must reflect the true Catholic Faith. In all its details, the Catholic Mass reflects what Catholics believe, and vice versa: What Catholics believe is reflected in the Holy Mass.
It therefore follows that if someone were to substantially change the liturgical actions or prayers of the Holy Mass, this would necessarily change or impact the belief of Catholics. It is clear, that if the Second Vatican Council changed the Faith, that a new act of worship would be produced which also needs a new priesthood, and with both there came new churches, that is, houses of worship that, likewise, no longer represented the Catholic Faith but rather reflected a new religion.
The “New Mass” is truly not the Mass that we must attend. The Tridentine Mass is the Mass of the Roman Catholic Church. We follow the liturgical laws prior to 1955 since the changes from that date were as steps leading to the "New Mass."