Q. Can a woman attend Israeli dance classes for girls & women only, instructed at a Non- Orthodox synagogue?

A. on question 126 in regards to a Jew who is alcoholic being permitted to enter a church (even possibly the main sanctuary) to attend an AA meeting, and in question 759 in regards to using a food bank also inside church facilities, we wrote; It is forbidden to enter a house of avodah zarah or a church. (Y.D. 150,1- 157,3 – Shach ibid. 149,1.) R’ Moshe Feinstein Zt”l (Igros Moshe O.C. 4,40,26) prohibits students playing ball in a sports hall that belongs to a church, even if no religious images are present. (See Rivavos Ephraim 3, 302,3) However Poskim do permit voting in a locale adjoining or connected to a church, which specifically set up a venue for that purpose and it is marked or is known to be so. This sanction is only ex post facto, when no other voting location was made available or is found close by. (Teshuvos Vehanchogos 2,410).
Horav Shlomo Miller Shlit”a permits using the AA church venue, if the meetings are not held in the sanctuary, and it is clearly identified or known as a setting for social or community activities.”
Although, a Non-Orthodox synagogue is obviously not a church, and the issues involved are different; in Halacha, entering it may carry some similar proscriptions.
Horav Shlomo Miller’s Shlit’a opinion is that, although it is not recommended, one cannot prohibit the attendance of otherwise proper and correct activities being housed and offered in the premises of a Non-Orthodox synagogue, as long as they are not activities created or promoted as the congregation’s programs, and they are not carried out inside the sanctuary.

Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a