I've never been to Israel, but from what travelers and Israelis themselves tell me, it's a deeply divided country. The majority of the population lives along the coast, and is quite secular, about as secular as Scandinavia. About 30% of the population is very pious, some militantly so, especially those in the settler movement. What adds to the deep mutual resentment between the pious and the secular populations is that most ultra-orthodox are exempt from military service.
Tel Aviv and Jerusalem are not only different cities, but different worlds. I remember one Israeli friend years ago telling me that Jerusalem is so soaked in religious associations that it literally drives people mad. Supposedly there is a hospital in Jerusalem that specializes in treating "Jerusalem Syndrome," the madness induced by the city's religious charisma. Friends tell me that there is a whole wing of that hospital for people who think they are Christ. My friend David Kaplan, who is seriously religious though not a fanatic, found the city to be too much. After a day praying at various religious sites, he had had enough and went back to his hotel and watched Simpsons reruns.