Let us first examine the elements of the Novus Ordo Missae. Some are Catholic:
but some are Protestant:
The Novus Ordo Missae assumes these heterodox elements alongside the Catholic ones to form a liturgy for a modernist religion which would marry the Church and the world, Catholicism and Protestantism, light and darkness. Indeed, the Novus Ordo Missae presents itself as:
Notice also the numerous rubrical changes:
Moreover, the Novus Ordo Missae defined itself this way:
The Lord’s Supper, or Mass, is a sacred synaxis, or assembly of the people of God gathered together under the presidency of the priest to celebrate the memorial of the Lord. (Pope Paul VI, Institutio Generalis, §7, 1969 version)
...the intention of Pope Paul VI with regard to what is commonly called the Mass, was to reform the Catholic liturgy in such a way that it should almost coincide with the Protestant liturgy... there was with Pope Paul VI an ecumenical intention to remove, or at least to correct, or at least to relax, what was too Catholic, in the traditional sense, in the Mass and, I repeat, to get the Catholic Mass closer to the Calvinist mass...*
*Jean Guitton on December 19, 1993 in Apropos (17), p. 8ff [also in Christian Order, October 1994]. Jean Guitton was an intimate friend of Pope Paul VI. Paul VI had 116 of his books and had made marginal study notes in 17 of these:
When I began work on this trilogy I was concerned at the extent to which the Catholic liturgy was being Protestantized. The more detailed my study of the Revolution, the more evident it has become that it has by-passed Protestantism and its final goal is humanism. (Pope Paul's New Mass, pp. 137 and 149. This latter is a fair evaluation when one considers the changes implemented, the results achieved, and the tendency of modern theology, even papal theology (cf. question 7).
It is the invention of a liturgical commission, the Consilium, whose guiding light was Fr. Annibale Bugnini (made an archbishop in 1972 for his services), and which also included six Protestant experts. Fr. Bugnini (principal author of Vatican II’s Sacrosanctum Concilium) had his own ideas on popular involvement in the liturgy (La Riforma Liturgia, A. Bugnini, Centro Liturgico Vincenziano, 1983), while the Protestant advisors had their own heretical ideas on the essence of the Mass.
However, the one on whose authority the Novus Ordo Missae was enforced was Pope Paul VI, who “promulgated” it by his apostolic constitution, Missale Romanum (April 3, 1969). However, his proscription was highly unclear.
Judging the Novus Ordo Missae in itself and in its official Latin form (printed in 1969)*, Cardinals Ottaviani and Bacci wrote to Pope Paul VI:
...the Novus Ordo represents, both as a whole and in its details, a striking departure from the Catholic theology of the Mass as it was formulated in Session XXIII of the Council of Trent. (A Brief Critical Study of the Novus Ordo Missae, September 25, 1969)
*A Novus Ordo Missae celebrated according to the 1969 typical edition would look very similar to the traditional Roman Rite, with the celebrant saying most (if not all) the prayers in Latin, facing the tabernacle and wearing the traditional Mass vestments, with a male altar server, and Gregorian chant, etc. None of the current abuses, e.g., Communion in the hand, Eucharistic Ministers, liturgical dancing, guitar-masses, etc., have part with this official form. Hence, the aforementioned cardinals' (as well as the SSPX's) critique of the Novus Ordo Missae is not of its abuses or misapplication, but rather of its essential and official form.
Archbishop Lefebvre definitely agreed when he wrote:
The Novus Ordo Missae, even when said with piety and respect for the liturgical rules, ...is impregnated with the spirit of Protestantism. It bears within it a poison harmful to the faith (An Open Letter to Confused Catholics, p. 29)
The dissimulation of Catholic elements and the pandering to Protestants which are evident in the Novus Ordo Missae render it a danger to our faith, and, as such, evil, given that it lacks the good which the sacred rite of Mass ought to have. The Church was promised the Novus Ordo Missae would renew Catholic fervor, inspire the young, draw back the lapsed and attract non-Catholics. Who today can pretend that these things are its fruits? Together with the Novus Ordo Missae did there not instead come a dramatic decline in Mass attendance and vocations, an “identity crisis” among priests, a slowing in the rate of conversions, and an acceleration of apostasies? So, from the point of view of its fruits, the Novus Ordo Missae does not seem to be a rite conducive to the flourishing of the Church’s mission.
No, for the indefectibility of the Church does not prevent the pope personally from promoting defective and modernist rites in the Latin rite of the Church. Moreover, the Novus Ordo Missae:
*Let us remember that a pope engages his infallibility not only when teaching on faith or morals (or legislating on what is necessarily connected with them) but when so doing with full pontifical authority and definitively (cf. Vatican I [Denzinger §1839]. But as regards the Novus Ordo Missae, Pope Paul VI has stated (November 19, 1969) that:
...the rite and its related rubric are not in themselves a dogmatic definition. They are capable of various theological qualifications, depending on the liturgical context to which they relate. They are gestures and terms relating to a lived and living religious action which involves the ineffable mystery of God's presence; it is an action that is not always carried out in the exact same form, an action that only theological analysis can examine and express in doctrinal formulas that are logically satisfying.
NB: It should be also be understood that the papal bull, Quo Primum is neither an infallible document, but rather only a disciplinary document regarding the liturgical law that governs the Tridentine Rite (cf. this Catholic FAQ for details).
This does not necessarily follow from the above defects, as serious as they might be, for only three things are required for validity (presupposing a validly ordained priest), proper:
However, the celebrant must intend to do what the Church does. The Novus Ordo Missae will no longer in and of itself guarantee that the celebrant has this intention. That will depend on his personal faith (generally unknown to those assisting).
Therefore, these Masses can be of doubtful validity.
The words of consecration, especially of the wine, have been tampered with. Has the “substance of the sacrament” (cf., Pope Pius XII quoted in principle 5) been respected? While we should assume that despite this change the consecration is still valid, nevertheless this does add to the doubt.
If the Novus Ordo Missae is not truly Catholic, then it cannot oblige for one’s Sunday obligation. Many Catholics who do assist at it are unaware of its all pervasive degree of serious innovation and are exempt from guilt. However, any Catholic who is aware of its harm, does not have the right to participate. He could only then assist at it by a mere physical presence without positively taking part in it, and then and for major family reasons (weddings, funerals, etc).