Question: May a Jew enter a mosque or church when there is a need to do so or to visit there as a tourist attraction?
Answer: The great Rambam in his commentary on the Mishnah Masechet Avodah Zarah (Chapter One) deduces from the words of the Mishnah there regarding an actual house of idol worship “that we are almost forbidden to look at it, let alone enter it.” The words of the Rambam are quoted as Halacha by the Shach (Yoreh De’ah, Chapter 149) as well as the other Acharonim (ibid). The Tosafot in Masechet Avodah Zarah (17b) deduce from the Gemara (ibid.) that one must distance himself even from the entrance of a house of idol worship as much as possible. Similarly, Maran Ha’Shulchan Aruch in Yoreh De’ah (Chapter 150, Section 1) rules that there is a Mitzvah to distance one’s self four Amot (approximately 6.5 feet) from a path of idol worship. Thus, if one is walking close to a house of idol worship, such as a church, one should distance himself at least four Amot from the entrance to this place, for it is well-known that Christian churches are considered houses of idol worship as they believe in another deity besides for Hashem. If so, it is certainly forbidden to actually enter their churches, for they are actual houses of idol worship.
The Evil Spirit Found in Houses of Idol Worship
Besides for the halachic prohibition to enter a church, Hagaon Harav Chaim Palagi writes in his Responsa Chaim Be’Yad (Chapter 26) that when one enters a church, a spirit of heresy immediately cleaves to him; even if it does not cause one to sin, nevertheless, one impurifies himself just by entering such a place. This is especially true when the one who enters this place is a member of the holy Jewish nation to whom the forces of impurity cling strongly. One who enters a house of idol worship requires repentance and atonement for one’s sin.
Based on this, it is clear that it is forbidden to enter a Christian church, for a church is a house of idol worship, as we have explained.
The Practice of Maran Harav zt”l While Serving as a Rabbi in Egypt
While Maran Rabbeinu Ovadia Yosef zt”l served as a Rabbi and Av Bet Din (head of the rabbinical court) in Egypt in the year 5708 (1948), he also served as Assistant Chief Rabbi of Egypt. The post of Chief Rabbi was held by a man by the name of Chaim Nachum Afandi who was close to the king of Egypt, a member of the Egyptian parliament in Cairo, and a member of the Academy of the Arabic Language, and was thus chosen for this position. During this period, a certain well-respected Christian diplomat passed away in Egypt and the government invited the country’s Chief Rabbi to represent the Chief Rabbinate and participate in the funeral services. Since the Chief Rabbi was in a weakened state, he requested that Maran zt”l attend the funeral in his place. When Maran zt”l heard that it was customary for all to file into the church where the deceased lay and listen to Christian prayers and the like, he notified the Chief Rabbi that under no circumstances would he agree to enter the church. The Chief Rabbi exerted much pressure on Maran zt”l to agree to go, for if no representative of the Chief Rabbinate would be present, this might cause a serious diplomatic incident to ensue. Nevertheless, Maran zt”l disagreed with his stance and claimed that, on the contrary, the participation of a rabbi at such an event is an unparalleled desecration of Hashem’s name and a disgrace of the Jewish religion in the eyes of the non-Jewish nations. He thus remained steadfast in his convictions and no representative of the Chief Rabbinate attended the funeral. Note: No fall-out ever resulted.
Installing Air Conditioners in a Church
Similarly, Maran zt”l was asked about an individual whose profession was installing air conditioning units who had just signed a large contract to install hundreds of air conditioners. Included in the deal was installing air conditioners in a church. He inquired whether he may continue his work or must he cancel the deal and as a result, incur a hefty financial loss as he would need to pay for penalties sustained. Maran zt”l answered that he may continue with his work on the condition that he himself would not enter the church; rather, his non-Jewish workers would have to install the air conditioners there. Maran zt”l added that he himself should not instruct the non-Jews to enter the church; rather, he should tell another non-Jew to hire him some non-Jewish workers and install the air conditioners. (He continues to provide copious sources for his view as is the practice of Maran zt”l. Unfortunately, we cannot discuss these reasons at length.)
Entering a Muslim Mosque
Regarding entering a mosque, the Rambam explains in one of his responses that Ishmaelites are not considered idol-worshippers since they believe in Hashem and there is no denial of Hashem in their religion or anything else that should cause them to be considered idol-worshippers. We are therefore lenient and sell our lands in Israel to Muslims during the Shemitta (Sabbatical) year based on the “Heter Mechira” process although it is forbidden to sell land in Eretz Yisrael to an idol-worshipper; this is because Muslims are not considered idol-worshippers. Based on this, mosques are not considered actual houses of idol worship and one may enter them according to the letter of the law.
Summary: It is absolutely forbidden to enter a house of idol worship. Included in this prohibition is entering a Christian church or other kinds of houses of idol worship in the Far East. Nevertheless, there is no halachic prohibition to enter an Muslim mosque; this is especially true when this is being done in order to pray there, such as at the graves of our forefathers in the Machpela Cave in Hebron.