Listening to some religious talk my husband was watching – something from a chabad rabbi, I believe. An interesting question posed in this talk (asked of someone who was frum – meaning observant; careful in the observing of a law, custom, religious ritual, or the like). “What were you before you were frum?” Answer: I was jewish.
Interestingly, when asked of a Christian (and I am by no means knocking Christians), the answer is “well…nothing”. The thing about being jewish, is that there is nothing you do or don’t do about being jewish. You simply are. It’s really kind of that simple. Being religious or observant or frum (or not being so) changes nothing of whether or not one is Jewish. It’s not something you can walk away from or sin yourself out of.