ROME  In comments on Sunday that could have broad implications in a period of intense religious conflict, Pope Benedict XVI cast doubt on the possibility of interfaith dialogue but called for more discussion of the practical consequences of religious differences.

The pope’s comments came in a letter he wrote to Marcello Pera, an Italian center-right politician and scholar whose forthcoming book, “Why We Must Call Ourselves Christian,” argues that Europe should stay true to its Christian roots. A central theme of Benedict’s papacy has been to focus attention on the Christian roots of an increasingly secular Europe.

In quotations from the letter that appeared on Sunday in Corriere della Sera, Italy’s leading daily newspaper, the pope said the book “explained with great clarity” that “an interreligious dialogue in the strict sense of the word is not possible.” In theological terms, added the pope, “a true dialogue is not possible without putting one’s faith in parentheses.”

But Benedict added that “intercultural dialogue which deepens the cultural consequences of basic religious ideas” was important. He called for confronting “in a public forum the cultural consequences of basic religious decisions.”