There is one universal church of the faithful, out of which no one at all is saved; and in which Jesus Christ himself is at once priest and sacrifice; whose body and blood, in the sacrament of the altar, are truly constrained under the species of bread and wine, which, through the divine power, are transubstantiated, the bread into the body, and the wine into the blood; that for the fulfillment of the mystery of unity, we may receive of that which he received of ours.
Another step was taken about 350 years later, when the Council of Trent declared the host an atoning sacrifice:
And, since in the divine sacrifice which is performed in the mass, the same Christ is contained and offered in an unbloody manner, who, on the altar of the cross, offered himself, with blood, once for all; the holy synod teaches that that sacrifice is, and becomes of itself, truly propitiatory, so that if, with a true heart and a right faith, with fear and reverence, we approach to God, contrite and penitent, we may obtain mercy and find grace to help in time of need. The Lord, forsooth, being appeased by the offering of this, and granting grace and the gift of repentance, remit crimes and sins, even great ones; for it is one and the same host, the same person now offering by the ministry of the priests, who when offered himself upon the cross, only in a different manner of offering; and by this unbloody sacrifice, the fruit of that bloody one are abundantly received; only far be it that any dishonor should be done to that by this. Wherefore according to the tradition of the apostles, offering is duly made, not only for the sins, pains, and satisfactions, and other necessities of the faithful who are alive, but also for the dead in Christ, who are not yet wholly cleansed.
This same council further declared:
If any one shall deny that in the sacrament of the most holy eucharist, there is contained really, truly, and substantially, the body and the blood together with the soul and divinity, of our Lord Jesus Christ, and so whole Christ, but shall say he is only in it in sign, or figure, or power, let him be accursed.
Not content with this it declares that:
If any one shall say that in the holy sacrament of the eucharist, there remains the substance of the bread and wine, together with the body and blood of our Lord Jesus Christ, and shall deny that wonderful and remarkable conversion of the whole substance of the bread into the body, and of the whole substance of the wine into the blood, while only the appearance of bread and wine remain, which conversion the Catholic Church most appropriately names transubstantiation; let him be accursed.
The Council of Tridentine says there is a whole Christ in every particle of the Mass:
If any one shall deny that Christ entire is contained in the venerable sacrament of the eucharist, under each species, and, when they are divided, under every particle of each kind; let him be accursed.
The climax of blasphemy is reached when the Council of Trent asserts: