Am I allowed to attend my friend’s wedding in a church? Are Jews allowed to enter churches at all?
Evangelical churches do not have icons or statues and it is certainly permissible to enter Evangelical churches. Catholic and most Protestant churches do have icons as well as paintings and sculptures. If you enter the church in order to appreciate the art with an eye towards understanding Christianity and the differences between Judaism and Christianity so that you can hold your own in discussions with Christians, then it is permissible. Participating in a church religious service is forbidden unless it is for learning purposes or unless it would be a desecration of God’s name if you don’t attend, as in the case of Chief Rabbi Sack’s attendance at Prince William’s wedding.
The answer is interesting firstly for its differentiation between the Christian Sects. Additionally it would seem that he would allow Jews to enter churches of all sects if the reason is educational - even during a service. This is certainly an original view. I vividly remember a Rabbi in the gush yeshivah who is also one of the Rav's students when asked whether one can visit the Churches in Jerusalem answering "It isn't Yahreg ve'bal Yavor (I.E a sin you should kill yourself rather then commit) but not much better".
Hat Tip: Book of Doctrines and opinons