"I certainly encourage married couples to pray for a good and happy sex life -- it's a way for them to become closer to God," the 43-year-old Roman Catholic monk told AFP.
"At first people are usually slightly shocked but at the same time happily surprised," says Knotz, who like all Catholic clergy has taken a vow of celibacy.
Knotz has held retreats with more than 3,000 devoutly Roman Catholic couples in Poland since 2000, with the tacit blessing of church superiors ... and an approving nod from secular therapists.
Couples are so eager to attend that his weekend and six-day workshops are booked solid for the next year.
"If you believe in God, then you believe God is involved in life, in love, marriage and in sex and sexuality -- it seems natural to talk about sex to remove taboos and the label of sinfulness," says the monk, who resides in a monastery of the Order of Friars Minor Capuchin in Stalowa Wola, southern Poland.
The friar admits the popular teachings of the Roman Catholic church on the subject of sex have been weak -- if not downright dissuasive.
"It's been labeled taboo or sinful," Knotz says, but is quick to point out that in keeping with the church's teaching, he preaches only about the joys of sex restricted to marriage between a women and men.
Both his book, entitled "The Act of Marriage", and his "Chance to Meet" website (http://www.szansaspotkania.net/), launched in 2004 and has both English and Polish versions, graphically explore the steamy details of divine love-making.
In a passage entitled the "theology of the orgasm", Knotz likens the peak of sexual excitation to meeting God in heaven.
"Love between a married couple expressed in sex, brings the human body closer to heaven. The ecstasy in the joy of sexual intercourse can be likened to the joy of eternal life," he says giving an unusual twist to the religious notion of eternal salvation.
"This is why the conjugal act allows spouses to begin to understand the sweetness of encountering God," Knotz concludes, and is quick to caution that "concentration on the physiological side of a sexual intercourse causes reduction of its most important elements."
-- Husbands must take time to 'fully appease' their wives --
Knotz also insists "good, open communication between spouses" is the best technique to achieve orgasms of heavenly proportions.
And he does not neglect women -- in strongly Catholic and conservative Poland where a Women's Party founded last year said the country's real political problem was not corruption or the legacy of communism but... male chauvinism.
He encourages husbands to take their time to "fully appease" their wives.
"When a woman is excited, she wants to experience absolute pleasure as much as a man does," the monk's website says. "The feeling of sexual dissatisfaction, for a woman who is already excited, is a great physical and psychological suffering."
Though his teachings do not skimp on spicy details, detractors argue that as a celibate man of the cloth he lacks the hands-on experience to speak credibly about sex.
"I look at it this way: you don't have to have a heart condition to be a cardiologist and you don't have to be an alcoholic to work as a therapist," he says unfazed.
The monk explains he was originally inspired by the open atmosphere of his family home and the early teachings of late Polish-born Pope John Paul II who broached the subject of sexuality in his book "Love and Responsibility", first published in 1960.
"The Holy Father's 'theology of the body' and other philosophical and theological works delve deeply into the divinity of sexual relations in marriage -- I'm just making these complex ideas more accessible to average Catholics," he says.
Kasia and Jan Paluszewski are true believers. Married for 18 years the parents of three children aged 16, 13 and three, they say Friar Knotz's teachings have "uplifted" and "enlightened" their sex life and spirituality.
"The workshops with Father Knotz really helped us to overcome our inhibitions and guilt regarding sex," Jan, a 46-year-old IT specialist from Poland's north-western Kujawsko-Pomorskie region told AFP. "He really listens to couples and this is why I think he understands us so well."
Psychotherapist Marek Ruzdziewicz says conventional sex therapy does not address or really consider spiritual aspects of sex.
"I never heard of it before meeting Father Ksawery," he told AFP. "It's a novel approach which in my experience helps couples achieve greater intimacy -- so why not?"