What is the reasoning for not entering churches and other non-Jewish places of worship?

Question

There are multiple questions about entering churches here, most of which are marked as duplicates and pointed to this one. What none of them address, however, is why in the halacha it is forbidden to enter a church or other non-Jewish place of worship. This question is aimed at understanding the reasoning in the scripture for not entering such a place.

A few of the above questions make arguments to this point. For example, this answer says the following:

One factor to keep in mind is how close one gets to the building itself as he notes, " While church services are being held, it is clearly forbidden to enter the church’s parking lot because it may seem to a bystander that one is entering the parking lot in order to enter the church. When church services are not being held, it is permitted to cut through the church’s parking lot...

This would seem to indicate that the problem is one of appearances. Were one to enter during off-hours, or in the dark, or ensure one were to remain unseen, perhaps the rule would not apply.

This answer states that the prohibition is not against entering church grounds, but rather against entering the sanctuary proper, the specific site of non-Jewish worship:

However, it is forbidden for a Jew to enter the sanctuary of the church, i.e. where the actual prayer services are held. As it is a marit ayyin as it could be interpreted as identification with the philosophy. However, it is permitted to enter other rooms in a church for non-religious purposes.

Depending on the interpretation of the word "interpreted" (which reminds me a bit of Bill Clinton's famous "It depends on what the meaning of the word ‘is’ is"), and the reference to marit ayin, this would appear to support the notion that the problem is one of appearances, that being in a church, for example, may cause onlooking Jews to believe that it is permissible to worship as a Christian; of course it is not.

Is it then to be taken that if one were surrounded entirely by non-Jews, with no Jews present, as is very likely the case in and around a church in a mostly-secular part of the world, that it is permissible to enter a church so long as one does not take part in the worship?

Answer 1

A not-always-known-fact about marit ayin is that it applies even when no one is watching. As the Rambam writes in Hilchot Shabbat 22:20

And [regarding] every place that the Sages forbade [something] on account of appearance, it is forbidden even in an inner chamber. [an expression meaning when the person is not seen by others]

(see also SA OC 301:45)

As such, since entering a church is forbidden by many, it doesn't help that there are no Jews around.

Beyond this R Chaim Palagi (quoted here) 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. [...] One who enters a house of idol worship requires repentance and atonement for one’s sin.

Answer 2

The problem is multi-layered. As you cited in your question there's an issue of appearances and making others believe you are taking part in a church activity.

Another issue is the nature of the location itself.

Churches are designed for implanting messages into a person's psyche.

This is extremely true for Catholic churches.

The stonework, the statues, the paintings, the layout, the designs in the windows, the songs they sing, the clothing of the clergy, etc.

These are buildings which have been created for a religious purpose and have been designed to promote a message and to implant that message into your psyche. Even if you reject Christianity consciously, the location is a house of foreign worship and there's a danger in trivializing the nature of the location as harmless. The location is designed to implant foreign teachings into your psyche.

If you are a religious person, you know the power of ritual and you know the power of surrounding yourself with Jewish ritual. Witnessing the Torah in Shul, lighting shabbat candles, hearing Jews daven, seeing a mezuzah on the door, all of these impart messages and teachings and impact your spiritual psyche as a Jew. This connection to your environment and your space of worship imparts something within you.

The same is true of Christian houses of worship.

It can be argued that standing inside of a church and looking around is like reading the New Testament in a certain sense. It's imparting a religious message and impacting you psychologically even if you aren't aware of it. The risk of that is great enough that the Rabbis ban us from entering them for the sake of protecting us from that risk.

I'm attaching a Chabad article which touches upon this question.

Answer 3

Rabbi Yosef Mizrachi says that a Church is a place of idols and a Reform shul is even worse. He says a mosque is ok. I disagree. A Jewish temple is preferable to another religion's place of worship, especially when Arabs are anti-semites right now.