Game over. Check mate. Irrefutable proof that NFP is condemned by the Church.
The 1930 encyclical Casti Connubii #59 speaks of the marital act:
"Holy Church knows well that not infrequently one of the parties is sinned against rather than sinning, when for a grave cause he or she reluctantly allows the perversion of the right order. In such a case, there is no sin, provided that, mindful of the law of charity, he or she does not neglect to seek to dissuade and to deter the partner from sin."
This "perversion of the right order" mentioned is not, and cannot be referring to artificial contraception.
Here's why. Contraception is intrinsically evil and can never be cooperated with, participated in, or allowed under any circumstances.
Consider this judgement by the Holy Office from April 19, 1853.
Can a wife be knowingly passive in condomistic intercourse?
Response: Negative; for it would be an
involvement in something intrinsically unlawful.
Any method of artificially thwarting the
telos of the act (procreation) is evil
because it renders the act "non marital"
and violates it's intrinsic nature. For
an act to be "marital," it must be
"suitable for the generation of children."
100% of contraception is unsuitable,
so it can never be tolerated by the
innocent spouse.
OK, but NFP is "natural." Fine - hold on.
What is "the perversion of the right
order?" It is the subordinating of
procreation to the secondary ends
of the conjugal act. Q.What "sin"
can the wife allow in CC 59? A. Onanism.
This is because Onanism is not immediately
illicit, but becomes so upon completion.
It is natural in execution, and unnatural in conclusion.
April 3, 1916 Sacred Penitentiary:
"Question: Whether a woman can lawfully
cooperate with a husband who, that
he may indulge in pleasure, wishes to
commit the crime of Onan or of the
Sodomites, and who threatens her
under the pain of death or grave
troubles, unless she complies?
Response: a) If in the use of marriage
the husband wishes to commit the
crime of Onan, namely, by losing his
seed outside the vas after intercourse
has begun, and likewise threatens his
wife with death or grave troubles,
unless she conform to his perverse
wishes, according to the opinion of
approved theologians the wife may
lawfully have intercourse with her
husband in this
case: to be sure, since on her part
she addresses herself to a lawful
thing and action, she is but permitting
the sin of the husband for a serious
cause which excuses her: since
charity, by which she is bound to
impede the sin, does not
oblige in so great inconvenience."
CC 59 is repeating this ruling when it says "for a grave cause he or she reluctantly allows the perversion of the right order."
In 1997, the Pontifical Council for the Family promulgated the Vademecum for Confessors.
Directly addressing our question, section 3:13:1 of the VFC states: "Special difficulties are presented by cases of cooperation in the sin of a spouse who voluntarily renders the unitive act infecund...This cooperation can be licit when...the action of the cooperating spouse is not already illicit in itself."
IOW, only deliberate "natural" infecundity can be reluctantly allowed by the innocent spouse, because to passively allow artificial contraception would be "already [immediately] illicit" and forbidden as non-marital.
So we have established conclusively that contraception can never, under any circumstances, be passively, reluctantly cooperated with, and that Onanism can be reluctantly cooperated with, because it is not initially unnatural. However, all measures which are taken to render the act infecund, are grave sin.
So how does this pertain to NFP? CC 59 "Holy Church knows well that not infrequently one of the parties is sinned against rather than sinning, when for a grave cause he or she reluctantly allows the perversion of the right order."
If the only sin which SHE can tolerate is onanism, what is the only sin that HE can tolerate?
Answer? NFP! The reason is because NFP, like onanism, is natural in execution - unnatural in conclusion (infecund). We know that CC 59 cannot be referring to artificial contraception, so that leaves only the natural perversion of the right order, aka NFP. CC 54 "the conjugal act is destined primarily by nature for the begetting of children." So when timing is used to render that conjugal act infecund (onanism or NFP), this sin can be tolerated because it is not "already illicit" (not immediately, but finally). The innocent spouse must communicate in charity to the guilty spouse that such infertility timing is grave sin.
The only way NFP flies today is by turning marriage on it's head and placing life at the service of love. If we can create a new essence of marriage based on love, then contraception is not immediately illicit, because then a "marital act" is redefined as suitable for the generation of love, with children being a secondary, dependent end on the primary and independent end, which would be love. Enter Vatican II: "Marriage...is not instituted solely for procreation." GS 50
Wrong! The conjugal act has only one instituted purpose, with other secondary purposes. When the secondary are made "institutional" purposes, procreation automatically becomes a secondary purpose because love is 24/7/365 but fertility is intermittent.
Everything "trans" today is simply a redefinition of nature (essence) which has it's genesis in modernism obfuscating marriage law to allow primary infecundity. Pius XII was the first to do this in his 1951 address to Italian Midwives. Ironically, Pius XII stated via his Holy Office decree of 1944 that making infecundity primary was a "revolutionary way of thinking and speaking [which] aims to foster errors and uncertainties."
In summary, NFP cannot be Catholic because Casti Connubii 59 says that the husband can reluctantly tolerate the sin (perversion of the right order) of the wife, and said sin cannot be contraception because contraception violates intrinsic nature, and is never to be cooperated with per the Holy Office, Sacred Penitentiary and Vademecum for Confessors. The only perversion of the right order (secondary over primary) remaining is calendar infertility aka NFP; and Casti Connubii says that this is a sin. One must either must trans essence and create a new hierarchy of ends, or abandon NFP as simply organic contraception. Vatican II did it's best to eliminate the hierarchy of ends, but no pope can change the essence of marriage.
Counterarguments encouraged.
-John Farrell