I'm in the middle of typing an e-mail to someone, but I thought that before I send this off I should post a piece of it, relevant to the topic.
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You write:
Far from a master of the segue Mgr. Fenton, with no proof whatsoever, concludes that the authors of the Fourth Lateran Council were following Augustine and that they had baptism of blood in mind.
I agree it isn't very probable at all that such a particular example was going through their minds. I think it would have been better if he had stated that they weren't unaware of the concepts of baptism of desire or blood. His argument surely relies on these doctrines, but his central point is that the Council Fathers never intended to say that "only members of the Church may obtain the Beatific Vision".
This is clear for two simple reasons. First, a year later, the pope who had presided over the council had wrote something that obviously betrays such an intention:
http://www.traditionalmass.org/articles/article.php?id=28&catname=2#_ftnref3Other theologians also cite Trent and Innocent II for these definitions. They also cite Pope Innocent III’s decree in 1206 concerning a Jєω who desired baptism but was not able to be validly baptized: “If, however, such a man had died immediately, he would have flown to his heavenly home at once, because of the faith of the sacrament, although not because of the sacrament of faith.” (Dz 413)[3]
Secondly, the Church has never condemned the doctrines of baptism of desire or blood. These doctrines effect (and has effected) how the Church deals with catechumens. The Church would never have permitted preachers/whomever else to exhort those who have not received baptism by water to face death rather deny Christ. For if encouraging them to suffer martyrdom than rather deny Christ would actually cause their damnation then truly it would have been better to exhort them to deny Christ and live, and seek a later time to undergo the rite of baptism.