Is it permitted to take part in the New Mass?
Even if the New Mass is valid, it displeases God in so far as it is ecumenical and protestant. Besides that, it represents a danger for the faith in the Holy Sacrifice of the Mass. It must therefore be rejected. Whoever understands the problem of the New Mass must no longer assist at it, because he puts voluntarily his faith in danger, and, at the same time, encourages others to do the same in appearing to give his assent to the reforms.
How can a valid Mass displease God?
Even a sacrilegious Mass celebrated by an apostate priest to mock Christ can be valid. It is however evident that it offends God, and it would not be permitted to take part in it. In the same way, the Mass of a Greek Schismatic (valid and celebrated according a venerable rite) displeases God insofar as it is celebrated in opposition to Rome and to the unique Church of Christ.
Can one attend the New Mass however when it is celebrated in a worthy and pious manner by a Catholic priest with a faith that is absolutely certain?
It is not the celebrant who is called into question, but the rite that he is using. It is unfortunately a fact that the new rite has given very many Catholics a false notion of the Mass, which is closer to that of the protestant last supper than that of the Holy Sacrifice. The new Mass is one of the principal sources of the current crises of the faith. It is therefore imperative that we distance ourselves from it.
Can one assist at the new Mass in certain circumstances?
We must apply to the new Mass the same rules we use for the attendance at a non-Catholic ceremony. One can be present for family or professional reasons, but one behaves passively, and especially does not receive Holy Communion.
What can one do when it is not possible to assist every Sunday a traditional Mass?
Whoever does not have the possibility to assist at a traditional Mass is excused from the Sunday obligation. The precept of the Sunday obligation only obliges in the case of a true Catholic Mass. One must however, in this case strive to assist at a traditional Mass at least regular intervals. What’s more, even if one is thus dispensed from assistance at Mass (which is a commandment of the Church), one is not thus so for the commandment of God (“Thou shalt sanctify the Day of the Lord”). One must replace, by one manner or another this Mass which one cannot have, with for example the reading of the text in one’s missal, and uniting the intention, during the time of the Mass to a Mass celebrated elsewhere, and in practicing a spiritual communion.