Several times I've seen a quotation from Pope John Paul II that seems to imply acceptance of naturism. I find this a bit odd for someone who is probably about as socially conservative as you can get. The quote is from "Love and Responsibility", published by Karol Wojtyla in 1960, eighteen years before he became Pope; the English translation was published in 1981. In the interest of research I put aside my principles and tracked down a copy of the book.
The quotation was given as:
Sexual modesty cannot then in any simple way be identified with the use of clothing, nor shamelessness with the absence of clothing and total or partial nakedness. There are circumstances in which total nakedness is not immodest... nakedness as such is not to be equated with physical shamelessness. Immodesty is only present when nakedness plays a negative role with regard to the value of the person... The human body is not in itself shameful, nor for the same reasons are sensual reactions, and human sensuality in general. Shamelessness (just like shame and modesty) is a function of the interior of the individual.
Pope John Paul II
It does not appear exactly like this in the book. It is made up of several smaller quotes from various parts of the text, but all from Chapter III "The Person and Chastity" second section "The Metaphysics of Shame", a section of twenty pages in which the word "shame" or its derivatives appear 170 times. Although the quoted words do appear they don't give a fair indication of the tone of the book.
Like other religious leaders, he seems convinced that the sight of naked bodies will inevitably arouse lust in the beholder, especially the male beholder, which is shameful:
Man, alas, is not such a perfect being that the sight of the body of another person, especially a person of the other sex, can arouse in him merely a disinterested liking which develops into an innocent affection.
The natural development of modesty in boys and men generally follows a different course. ... For him, sexual values are more closely bound up with the 'body and sex as potential objects of enjoyment', this is the form in which he becomes aware of them, and experienced in this way they become for him a cause of shame. He is, then, ashamed above all of the way in which he reacts to the sexual value of persons of the other sex. He is equally ashamed of sexual values connected with his own 'body'.
There is a lot of argument to explain how it is then possible to procreate without shame, which is because the love in a committed, indissoluable marriage, for the express purpose of procreation, absorbs shame. Under those circumstances nakedness is not shameful. There are also circumstances, such as medical examinations, where nakedness is not necessarily shameful. It is also, he says, acceptable to wear a swimming costume while swimming, but not while out walking.
Interestingly, he mentions primitive peoples who might be always naked and not ashamed and from this infers that nakedness does not ncessarily give rise to sexual shame:
...in tropical conditions primitive peoples live in partial or total nakedness. Many details in their way of life indicate the nakedness cannot be simply and unambiguously indentified with shamelessness.
but does not enlarge on how this is possible if man is incapable of looking at a naked body without shameful reactions. Perhaps the primitive peoples are more nearly perfect, at least before the missionaries get to them.
Below are the complete paragraphs which contain the extracts (bold) in the quotation:
Page 175: We are specifically concerned with sexual shame. Its external manifestations are connected with the body - it is to some degree physical shame. Particular objects of shame are those parts and organs of the body which determine its sex. Human beings show an almost universal tendency to conceal them from the gaze of others, and particularly of persons of the other sex. The largely explains the need they feel to avoid nakedness. Obviously other motives are at work here, particularly the organism's need for protection against cold, which is more or less important in particular climates: in tropical conditions primitive peoples live in partial or total nakedness. Many details in their way of life indicate the nakedness cannot be simply and unambiguously indentified with shamelessness. On the contrary, for some primitive peoples, the concealment of parts of the body previously exposed is a manifestation of shamelessness. We doubtless see here the effect of habit, of a collective custom which has evolved under the influence of the prevailing climate. Nakedness assists the adaptation of the organism to climatic conditions and no other intention can easily be found in it, whereas other motives can easily be assigned to concealment of those parts of the body which distinguish male and female. We find that dress may serve not only to conceal but in one way or another to draw attention to these parts of the body. Sexual modesty cannot then in any simple way be identified with the use of clothing, nor shamelessness with the absence of clothing and total or partial nakedness. This is a secondary and variable factor. The most we can say is that a tendency to cover the body and those parts of the body which declare it male or female goes together with sexual shame but is not an essential feature of it.
Page 190: This does not, however, mean that physical shamelessness is to be simply and exclusively identified with complete or partial nakedness. There are circumstances in which nakedness is not immodest. If someone takes advantage of such an occasion to treat the person as an object of enjoyment, (even if his action is purely internal) it is only he who is guilty of shamelessness (immodesty of feeling), not the other. Nakedness as such is not to be equated with physical shamelessness. Immodesty is present only when nakedness plays a negative role with regard to the value of the person, when its aim is to arouse concupiscence, as a result of which the person is put into the position of an object for enjoyment. What happens then may be called "depersonalization by sexualization". But this is not inevitable. Even when nakedness goes with mutual sexual enjoyment respect for the dignity of the person can be fully preserved. This is how it must be in marriage, where there exist the objective conditions for the genuine absorption of shame by love. We shall return to this in the next chapter. In any case, unless we take this view of the role of the body in love between persons, we cannot speak of modesty and purity in married life, though these are of permanent and fundamental importance in Catholic teaching.
Although physical immodesty cannot be identified in a simple way with nakedness as such, it none the less requires a real internal effort to refrain from reacting to the naked body in an immodest way. It should however be added that there is a difference between immodesty in feelings on the one hand and reflex sexual reactions to the body and sex as a 'possible object of enjoyment' on the other. The human body is not in itself shameful, nor for the same reasons are sensual reactions, and human sensuality in general. Shamelessness (just like shame and modesty) is a function of the interior of a person, and specifically of the will, which too easily accepts the sensual reaction and reduces another person, because of the person's 'body and sex', to the role of an object for enjoyment.