I grew up Jewish Orthodox. It's probably the strictest most life encompassing religion ever followed. From the moment you wake up in the morning until you close your eyes at night there is nothing you do without saying a blessing. There is even a blessing for when you go to the bathroom.
I've often wondered how it became like that and I have a theory. While we live in Eretz Yisrael there was no reason for us to differentiate ourselves from others. There was no need to strive to keep our identity. Everyone was Jewish. Then the unthinkable happened and we were conquered and thrown off our land. The whole fabric of our existence was destroyed and a set of intricate ritulas and prayers and blessings were put in place to help remind us that we were indeed different.
As the years went by some strayed while others became more obstinate in their preservation of Judaism. Rules got stricter, rituals became more meaningful. Various communities developed their own minhagim (habits-ways of doin things) based on the constraints of the societies they lived in.
After two thousand years what we had was the most obstinate of the original Jews clinging to their identity with a maze of laws and rituals.
Then we returned to our land.
Most Israeli's are secular. The majority do have a belief that god exists but they don't follow the religion. About 25% are non believers but still consider themselves Jews.
I got into an argument with several people about being able to be an atheist or agnostic and still be Jewish. After all, you can't be a Christian or Muslim of you don't believe in God. I had someone else tell me that she dated a Jewish guy once and felt alien. It was like everyone else belonged to this exclusive club and she didn't. I understand why she felt that way. After so many years of preserving our way of life there is an intangible bond between us. It has nothing to do with god it's genetics. Those of us who preserved our identity carry certain genes, traits that are unique to our "family". We can sense each other. It isn't "mystical" it's biological.
Regardless of what you believe you are Jewish if your mother was Jewish. We are in a sense a spread out collective that can't agree on anything. Being Jewish is a trip. I love it and wouldn't want to be anything else. But I can totally understand why other people don't get us.