Those who attack the Church of Christ by teaching that Christ's Church is divided into so-called 'branches' which differ in doctrine and way of life, or that the Church does not exist visibly, but will be formed in the future when all 'branches' or sects or denominations, and even religions will be united into one body;
“The Christian faithful are therefore not permitted to imagine that the Church of Christ is nothing more than a collection — divided, yet in some way one — of Churches and ecclesial communities; nor are they free to hold that today the Church of Christ nowhere really exists, and must be considered only as a goal which all Churches and ecclesial communities must strive to reach”. In fact, “the elements of this already-given Church exist, joined together in their fullness in the Catholic Church and, without this fullness, in the other communities”. “Therefore, these separated Churches and communities as such, though we believe they suffer from defects, have by no means been deprived of significance and importance in the mystery of salvation. For the spirit of Christ has not refrained from using them as means of salvation which derive their efficacy from the very fullness of grace and truth entrusted to the Catholic Church”. (Pope John Paul II, Joseph Cardinal Ratzinger, Declaration Dominus Iesus §17)
who do not distinguish the priesthood and mysteries of the Church from those of the heretics, but say that the baptism and eucharist of heretics is effectual for salvation;
This, on the other hand, according to the perpetual consent of the Catholic Church, is incorrect. Heretics, indeed, cannot receive the sacraments unto salvation; this does not mean, however, that those sacraments are not sacraments of the Church which are truly effectual for salvation. St. Augustine, defending against the Donatist heretics, makes this distinction clearly:
And what they themselves think that they conferred on those persons whom Felicianus baptized in schism, when they admitted them to reconcilation with themselves, viz., not that they should receive that which they did not as yet possess, but that what they had received to no advantage in schism, and were already in possession of, should be of profit to them, this God really confers and bestows through the Catholic communion on those who come from any heresy or schism in which they received the baptism of Christ; viz., not that they should begin to receive the sacrament of baptism as not possessing it before, but that what they already possessed should now begin to profit them. (On Baptism, Against the Donatists, I, 5:7)
St. Alphonsus Liguori notes: "Thus also Concina and Antoine say that it is not licit to seek the Sacraments from a heretic and/or schismatic, except in the case of extreme and/or the most grave necessity" (Theologia Moralis, Vol. III, Tract I, Chapter III, No. 89). Obviously this could not be possible at all if the sacraments of heretics were not, in fact, effectual to salvation for those belonging to the the one, holy, catholic, apostolic, and Roman Church.
This statement conflicts with the teaching of the Orthodox Church: "Obviously this could not be possible at all if the sacraments of heretics were not, in fact, effectual to salvation for those belonging to the the one, holy, catholic, apostolic, and Roman Church."
Apostolic Canon XLVI.
We ordain that a bishop, or presbyter, who has admitted the baptism or sacrifice of heretics, be deposed. For what concord hath Christ with Belial, or what part hath a believer with an infidel?
Apostolic Canon XLVII.
Let a bishop or presbyter who shall baptize again one who has rightly received baptism, or who shall not baptize one who has been polluted by the ungodly, be deposed, as despising the cross and death of the Lord, and not making a distinction between the true priests and the false.
Apostolic Canon LXVIII.
If any bishop, presbyter, or deacon, shall receive from anyone a second ordination, let both the ordained and the ordainer be deposed; unless indeed it be proved that he had his ordination from heretics; for those who have been baptized or ordained by such persons cannot be either of the faithful or of the clergy
THE BEGINNING OF CANON 2 OF THE COUNCIL "IN TRULLO": Declaring the Apostolic Canons to be a part of Orthodox canon law.
"It has also seemed good to this holy Council, that the eighty-five canons, received and ratified by the holy and blessed Fathers before us, and also handed down to us in the name of the holy and glorious Apostles, should from this time forth remain firm and unshaken for the cure of souls and the healing of disorders. And in these canons we are bidden to receive the Constitutions of the Holy Apostles [written] by Clement."