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The Rev. Ksawery Knotz has a message for all married Catholic couples out there: there's nothing wrong with a steamy sex life.

In fact, it's a good thing.

In his new book "Sex as you don't know it: For married couples who love God," the Polish friar provides a theological and practical guide for Catholics that has little in common with the strait-laced attitudes often associated with the Roman Catholic Church.

"Some people, when they hear about the holiness of married sex, immediately imagine that such sex has to be deprived of joy, frivolous play, fantasy and attractive positions," Knotz writes. "(They think) it has to be sad like a traditional church hymn."

But Knotz, a Franciscan friar from a monastery outside Krakow in southern Poland, wants to change all that. His book aims to sweep away the taboos and assure Catholic couples that good sex is part of a good marriage.

"The most important message is that sexuality does not deviate at all from religiousness and the Catholic faith, and that we can connect spirituality and a search for God with a happy sex life," Knotz told The Associated Press by telephone.

Much of the book stems from questions that Knotz encountered while counseling married couples.

"I talk with a lot of married couples and I listen to them, so these problems just kind of sit in my mind," he said. "I would like for them to be happier with their sex life, and for them to understand the Church's teachings so there won't be unnecessary tension or a sense of guilt."

Clergymen, including Knotz's countryman Pope John Paul II and his successor Pope Benedict XVI, have written about the ethics of love, marriage and sexuality before, and laymen have penned steamy sex guides for married Catholic couples.

But few if any priests have taken Knotz's explicit approach to sex — including everything from the theological to the practical, from oral sex to contraception and the number of children a Catholic couple should have.

"Every act — a type of caress, a sexual position — with the goal of arousal is permitted and pleases God," Knotz writes. "During sexual intercourse, married couples can show their love in every way, can offer one another the most sought after caresses. They can employ manual and oral stimulation."

The book falls squarely within the commonly held view of the Church's teaching on sex: Knotz discourages the use of condoms or birth control pills, and says they "lead a married couple outside of Catholic culture and into a completely different lifestyle."

But some Poles have been surprised by the overriding message of the book: sex is an important way for a man and wife to express their love and grow closer to God.

"Married couples celebrate their sacrament, their life with Christ also during sex," Knotz writes.

"Calling sex a celebration of the marriage sacrament raises its dignity in an exceptional way. Such a statement shocks people who learned to look at sexuality in a bad way. It is difficult for them to understand that God is also interested in their happy sex life and in this way gives them his gift."

The book received the necessary approval from Poland's church authorities that it is theologically in line with Catholic teachings. There also has been no sign of a backlash in the heavily Catholic and conservative homeland of the late Pope John Paul II.

Still, Knotz acknowledges that a priest writing a book about sex "is in and of itself a bit of a sensation."

The book hit stores across Poland last month. The Sw. Pawel publishing house has ordered a reprint after readers quickly snapped up the first 5,000 copies.

The publisher said it is in talks about possible English, Italian and Slovakian translations of the Polish-language book.