Is it a sin to enter a non-Catholic place of worship?

I just asked this question in “Ask an Apologist”, but I will ask it here also.

I have a missal from the '50’s (not mine, I’m only 24) but in it it mentions that entering a non-Catholic or non-Christian (I think it is actually non-Catholic, which is even more restrictive), place of worship is a sin. Now I know that most people nowadays would NOT consider it a sin to simply enter a Mosque or Buddhist temple, as long as you didn’t participate in their ceremonies, but if it was a sin in the 50’s, is it not still a sin today?

Thanks in advance!

Does your missal give a source? I doubt that the Church has ever explicitly taught that.

I would appreciate having the context.
Thank you.

I just got out my missal from the 50’s which I used through grade school and Id do not see anything like this. Could you possible quote what you read?

I don’t think it so. There’s no scandal if you go to a non-Catholic church to witness a wedding between two non-Catholics. Nor would there be scandal for merely visiting a non-Christian place of worship. That said, one should exercise caution. For example, in Japan there is a shrine dedicated to the spirits of those who committed atrocities against the Korean and Chinese people during the Second World War - merely visiting such a shrine incurs the scandal of showing reverence for these monsters.

Hmm so what it says is a little different to what I thought. It is in the context of an examination of conscience for confession, and considering the 10 commandments.
With regard to the first commandment it says “Have you ever… Gone to places of worship belonging to other denominations”.

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