There seems to be a belief that all non-frum Jews in Israel are atheists. But from my experience and from the number of Israelis who observe some mitzvos, that isn’t the case. For instance, the majority of Jews in Israel fast on Yom Kippur (see the YWN article on this last fall). The militant atheists are a small fraction of hilonim. Most fall into the “spiritual but not religious” classification, i.e. they believe in a Deity, in right and wrong, the existence of a soul, etc. but don’t affiliate with any established religion. In Israel, most identify as Jews and keep many traditional practices, but don’t care to join up to a fully-observant lifestyle. Take a look at how successful kiruv efforts have been, and how many children of non-chareidi parents are going to religious schools.
In fact, one could think that the strident, in-your-face attitude and political involvement of the most visible Hareidi groups might have some off-putting influence on Israelis, who for very good reasons are skeptical of politics in general. And looking down on them because “they’re all atheists” isn’t going to be much of a draw either.