[I]t is certainly at least conceivable that there is at least one psychopathic person out there impersonating a Roman Catholic priest or even bishop on a daily basis, with no plan to reveal the truth. That priest may even be the one who married (maybe I should put "married") you and your spouse, who hears your confessions, and who will perform last rites for you.Okay, for the sake of argument we can grant this. However in reality this is practically impossible, since bishops are publicly consecrated (as are priests).
If it turns out that the priest is a fraud, then none of the bread you ate was the body of Christ (nor was the wine his body [sic]), you have lived in unconfessed and unrepetant [sic] adultery (in fact all of your sins are unconfessed), and you will have died (without intending to do so) in a state of final impenitance [sic].I grant that - given the absurdly unlikely conditions assumed above - the people of such a parish would be without the true Body and Blood of Christ in Holy Communion. But this fact does not prevent anyone from getting to heaven: it is a matter outside of their control and knowledge (assuming, again, that they had no reason to question the legitimacy of the priest's consecration). An example might be a convert in a concentration camp who never has opportunity to receive Communion.
As to confession: it is not true that one's sins are "unconfessed" in this circumstance. "Only God forgives sins" (CCC 1441). He has simply given priests the power to do this in his name. God has bound reconciliation and forgiveness to the sacrament of confession, but he himself is not bound by his sacraments (cf. CCC 1257). Just as a man is saved who wishes to be baptized but does not have the opportunity (for example, because he dies during while still a catechumen), so too a man who dies but is truly sorry for his sins and who would gladly confess them if given the opportunity is not condemned because his circumstances did not permit him to receive the sacrament.
So even in the absurd circumstance described above, the truly contrite would not be held accountable for what it is not possible for them to have known. This is consistent with confession of mortal sin: we cannot confess what we do not remember. If we have truly forgotten some grave sin, but are otherwise truly contrite for our sins, and if we would have certainly confessed them had we remembered them, then they are treated as forgiven: "All mortal sins of which penitents after a diligent self-examination are conscious must be recounted by them in confession" (CCC 1456, quoting the Council of Trent, 14th Session, On the Most Holy Sacraments of Penance and Extreme Unction, Chapter V). Now, if they discover before death that they have been deceived, then they must be diligent to make a good confession to a priest. But to die in ignorance like this would not doom them.
And there are a couple other observations to be made: first, repentance comes before confession, so they would not be "unrepentant" as Turretinfan suggests. Second, his parenthesis "(without intending to do so)" reveals an apparent misunderstanding about how Catholics understand the problem of sin. Following his example sin of adultery: if a man sleeps with another woman because he falsely believes that she is his wife (either because he is blind, or because it is dark, etc), he has not intended to sleep with another woman. Consequently he is not culpable. It is still a gravely immoral act, but he is not guilty because he did not do it deliberately. "For a sin to be mortal, three conditions must be met: 'Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent'" (CCC 1857). So absent the deliberate intent and full knowledge of their true circumstances (of which, in the absurd case above, they are ignorant), such people would not be held culpable as though they had not genuinely confessed.
There is, one supposes, even a real question about whether you were ever baptized, since baptism by a non-believer has not traditionally been considered a valid baptism.In the first place, the original circumstances did not specify that the bogus priest was not Catholic. Clearly he would be in grave sin, and presumably he would hold seriously heretical ideas if he pursued this course for any length of time - but heresy on the part of the minister of Baptism does not invalidate the sacrament, just as other sins do not invalidate it. This is why Catholics accept Protestant baptisms as valid: their doctrinal errors are not relevant to the validity of the sacrament, as long as it follows the Trinitarian formula.
In the second place, baptism by a non-believer is considered valid: "In case of necessity, anyone, even a non-baptized person, can baptize, by using the Trinitarian baptismal formula" (CCC 1256). So it is incorrect to say that there is any question at all about the baptism, assuming that the Trinitarian formula was used. To assert that it "has not traditionally been considered" valid for a non-Christian to baptize is irrelevant to the question at hand, since the absurd circumstances described did not specify any specific era when the fraud is assumed to have occurred. Whatever the past might hold with respect to this question (I did a brief search but could find nothing about it), it is irrelevant today.
But even if we grant Turretinfan's doubt, and assume that the people in question were not validly baptized thanks to the fraud, it does not follow that they are in any danger whatsoever: for we believe that baptism of desire is legitimate. A man who genuinely desires baptism but cannot receive it due to circumstances beyond his control (for example, premature death) is not doomed to hell at all (CCC 1258, 1259). Hence Turretinfan's proposed concerns for such people are entirely needless.
The point is this, if you think that participation in the sacraments is a necessary part of salvation, and if you agree that sacraments performed by a faux priest are not valid, you can have only a tenuous assurance of salvation.There are different sorts of necessity, and we must be careful lest we stumble into equivocation here. If I wish to see in a dark room, it is necessary that I turn on a light. If I wish to survive, it is necessary that I eat and drink. These are two different sorts of necessity. Now, in the present case: reception of the sacraments is only conditionally necessary. Ordinarily Baptism is necessary for salvation, but not absolutely so: as noted above, there are cases where it is not. A baby has not committed any sins, and consequently for him the sacrament of Penance is not necessary. A man who does not have access to the Eucharist is not doomed to hell because his circumstances do not permit him to receive Communion. A woman cannot receive the sacrament of Holy Orders, and a priest cannot receive the sacrament of Holy Matrimony - so these two also are not "necessary for salvation" in the sense that Turretinfan seems to mean. The same may be said of Confirmation and the Anointing of the Sick.
Now it is of course true that ordinarily we must receive the sacraments. But the fact that there are exceptions demonstrates that salvation is not bound to them in the way that Turretinfan seems to suggest. So, if through no fault of their own some group of people is deprived of the sacraments - as, for example, in the absurd case of a fraudulent priest suggested by Turretinfan above - these people are not under condemnation at all. So the conditions of "tenuous assurance" that he suggests simply do not pertain to them.
And that is not Christianity. Salvation does not depend on human merit, human activity, or the faithfulness of the men who administer sacraments. Salvation depends on the action of God alone.But of course what he has described is not Catholicism, either. So we can agree that it is not Christianity, but only a distorted picture of it. The only thing worth clarifying here is that the validity of the sacraments does not depend upon the sanctity of the priest (here I am assuming that we are back in the real world once again, where priests are validly consecrated): it is the priest who gravely sins if he administers the sacraments while in sin himself; the people themselves are not ordinarily responsible (nor competent) to evaluate his standing before God.