Lyric discussion by Clocker 

While sin does have religious connotation, it doesn't have to mean sex itself. It could mean having bad thoughts about sex. According to Christianity, immoral sex is any sex outside of marriage is a sin, and is considered adultery.

So, I don't think this is about sex per say.

To me, this song is about all the feelings you get when you are in an intimate relationship. Especially in a long term relationship, you get annoyed, and sometimes being annoyed will lead to fights. Then comes the feelings you get when you reconcile those conflicts. not to mentions all the other kinds of feelings you get too, such as when you randomly think about you loved one.

There is also insecurity of all sorts. insecurity for when you are out of work and not able to take care of your loved one. Insecurity when you see your loved one with someone you don't know.

Then there's absolutely lustful thoughts like wanting to see your loved one naked.

Without specifics anything else is inferred.

@Clocker I think Christianity is a little more diverse than that these days. I mean, as they've diversified, there have been more groups that are not such extremists. (At least they don't blame "the Jews" collectively for killing Jesus. Someone I know once suggested that Judaism is responsible for only 2 major evils in the world: Christianity & Islam.)

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