CHAPTER 5. Why does the New Mass seem radically different from the traditional Latin Mass? It was conceived of as an “assembly” rather than a “sacrifice.” The 1969 General Instruction on the Roman Missal presented the underlying theological principles for the creation of the Mass of Paul VI.
In this document, the essence of the Mass is no longer “sacrifice” but “assembly” — a notion rooted in the ecumenical and modernist eucharistic theology of Louis Bouyer, who in turn based it on the writings of the 1930s Swedish Lutheran ecumenist Yngve Brilioth.
The Instruction also invented other “real” presences to undermine belief in THE Real Presence that occurs through transubstantiation, a dogma detested by Protestants and modernists alike.
Why are celebrations of the New Mass so different from church to church?
The Instruction “deregulated” the Mass by opening it up to “legitimate variations and adaptations” which can undermine Catholic doctrine and make visiting an unfamiliar church for Mass an adventure in liturgical surprises.
“Cekada rightly points out that the 1969 text [of the General Instruction] confidently outlined the prevailing theological principles that underpinned the reformed rite of Mass, which was published with it.
“Cekada demonstrates well… that these principles leave traditional Catholic theology behind: ‘sacrifice’ is replaced with ‘assembly’, ‘the Lord’s supper’ moves in to displace ‘the Sacrifice of the Cross’, etc.”
— Dr. Alcuin Reid
The Organic Development of the Liturgy