The Church emphasizes liturgical unity, particularly as it relates to the Novus Ordo, through several key principles:

Liturgy and Church Unity

• Expression of Church's Fundamental Notes: A correct understanding of the liturgy should clearly express the fundamental characteristics of the Church, especially the unity of the assembly gathered in the name of the Lord 1. Ritual unity should be perceptible across different generations, backgrounds, and cultures, avoiding opposition between the universal and the particular 1.
• Sacrament of Unity: Liturgical celebrations are not private events but celebrations of the Church, which is the "sacrament of unity" 2. They should be carried out in communion with the Church 2. The Church is a "holy people united and organized under their bishops," and liturgical actions pertain to the whole body of the Church, manifesting and affecting it 3.
• Eucharist as a Sign and Cause of Unity: The Eucharist is the sacrament that both signifies and brings about the unity of the Church 4. Celebrating it well is crucial for fostering the faithful's participation, allowing them to offer themselves with the priest, be drawn closer to God, and unite with one another 4.

Fidelity to Tradition

• Apostolic Tradition: Unity amid the diversity of liturgical traditions is assured by fidelity to the apostolic Tradition, which includes communion in faith and sacraments received from the apostles, guaranteed by apostolic succession 5.
• Harmony with the Universal Church: Particular Churches must align with the universal Church regarding the doctrine of faith and sacramental signs, as well as usages universally handed down by apostolic tradition 6. This ensures the integrity of the faith passed on, as the Church's rule of prayer (lex orandi) corresponds to her rule of belief (lex credendi) 6.
• Living Tradition: Tradition is a living reality that includes the principle of development and progress 7. The liturgy, as a privileged witness to the living Tradition of the Church, maintains a constant relationship between healthy tradition and legitimate progress 7.

The Novus Ordo and Liturgical Reform

• Renewal and Adaptation: The Second Vatican Council sought to renew and adapt the liturgy to meet contemporary needs, with the aim of promoting full, conscious, and active participation of the faithful 8 9. This was a primary objective behind the liturgical reform 8.
• Unique Expression of the Roman Rite: The liturgical books promulgated by Popes Paul VI and John Paul II, in accordance with the decrees of Vatican II, constitute the unique expression of the lex orandi of the Roman Rite 8. The Roman Rite, adapted over centuries, should be preserved and renewed in faithful observance of Tradition 8.
• Avoiding Division: The choice of celebrations according to pre-Vatican II liturgical books should not lead to a rejection of the Church and its institutions 2. Using the liturgy to promote ideological viewpoints that create division is discouraged 10.
• Liturgical Formation: Continuous liturgical formation is necessary for both priests and lay faithful to rediscover the value of the liturgical reform and preserve the truth and beauty of the Rite 10.

Respect for Diversity

• Inculturation: The Church respects and fosters the spiritual adornments and gifts of various races and peoples, integrating elements of their way of life into the liturgy, provided they harmonize with the true liturgical spirit 3.
• Variety within Unity: The variety of local Churches, each with its own discipline and theological and spiritual heritage, demonstrates the catholicity of the undivided Church, as long as they maintain unity of faith and the unique divine constitution of the universal Church 3.

In summary, the Church clarifies that liturgical unity is paramount, emphasizing that the liturgy is a celebration of the universal Church, fostering communion and avoiding division. The Novus Ordo, born from the liturgical reforms of Vatican II, is the primary expression of the Roman Rite, intended to promote active participation and a deeper understanding of the faith, while respecting the Church's living Tradition and allowing for diversity within unity.