Religious beliefs is not a first date conversation topic but its definitely something that should be brought up in the early stages of any relationship. And for OP to decorate his house like that, I can only assume that you guys have been dating for awhile. YDI.

he must really trust you considering he didn't bother telling you about his religion. Was there not any sign around the house that gave them away?

Why would you decorate anyone's house without permission? It's kind of an insult that you would feel they need to decorate for a holiday. If that's your tradition at your house great. Don't make someone celebrate the way you do.

As a rebuttal to the the discovery of your BFs religious preference you could have just said it was a Chanukah Bush.

Um yeah. if you know each other well enough to be alone in each other's place... then u should know his religion.

I'm going to go with what everyone else seems to be saying here. Obviously OP has been dating her boyfriend for long enough to where she should have some sort of idea as to his religion. Usually while getting to know someone in the early stages of dating you talk about your childhood and how you were raised. So I'm thinking they weren't dating long enough for her to pull this decorating stunt or she just never paid attention...

I'm Jewish and I have a Christmas tree so I don't think it's going to be a problem

YDI for assuming he's a Christian.

If you don't know him well enough to know he's Jewish you don't know him well enough to decorate his house! YDI!

Decorated as in Xmas or fully? At least one can be taken down.