Is it Permissible to Enter a Mosque?

Greetings, It is permitted for you to enter a mosque (see She'elot u'Teshuvot Yabia Omer, part 7, Yoreh De'ah section 12, and part 10, Orach Chaim section 16. The same is stated in the book Ashrei Ha'Ish, Yoreh De'ah part 1, chapter 10, paragraph 10, citing Rabbi Yosef Shalom Elyashiv, of blessed memory). However, it should be known that there is an absolute prohibition against entering churches and monasteries (see Yabia Omer, part 2, Yoreh De'ah section 11, and part 7 there. Also refer to She'elot u'Teshuvot Yechaveh Da'at, part 4, section 45. It is clear that it is certainly forbidden to visit Christian churches. Tour guides must be very careful to avoid causing Jews visiting Israel to stumble or be led to churches of Christians, for this violates the commandment "do not place a stumbling block before the blind." May those who listen find it pleasing, and may a blessing for good come upon them).

 Sincerely, Hillel Meirs