Recently, my teenage daughter experienced a formative moment: someone expressed negative feelings about her Jewishness. Frankly, I was thrilled. The fact that she has faced a moment common to all of us with Jewish identity means my plan to raise my children with strong connections to both Judaism and Christianity is working.
My children, with only one Jewish grandparent, could have passed as Christians. But that was not our family strategy. Our intention was to make them equally proud, equally knowledgeable, about both family religions, so that when this formative moment arrived, they would stand up as Jews, and feel the bracing sting of being outsiders, rather than duck and pass.
I am quick to identify myself as Jewish, particularly to Christians and Muslims, when I sense an opportunity to further the cause of interfaith dialogue, or to dispel prejudice or misunderstanding.
Ironically, with fellow Jews I am more likely to identify myself as an interfaith child. This is a defense mechanism (many wouldn’t consider me Jewish anyway because I’m a patrilineal “half-Jew“). But it is also another part of my mission to educate: I want my fellow Jews to try to understand bothness, interfaithness, the extent to which multicultural people cannot be described in binary terms. And I want them to understand that, although I don’t describe myself as a flat-out Christian for theological reasons (I do not believe Jesus was the messiah), I feel my interfaith status gives me permission to explore all that is inspiring and profound in Christianity.
I am Jewish. I am an interfaith child. I am both. And I claim the right to bodysurf these waves of fluid identity as the spirit moves me. I stand bobbing in the ocean, lifting gently off the sand for small waves, throwing my body ahead of the larger ones, catching exhilirating rides. I am not intimidated by the power of religious tides and spiritual currents. I am in my element, and the water is fine.
Being Both 
I already commented on your bio, but just had to add this about being “raised atheist” in a Jewish neighborhood. Classmates used to ask, “Are you Jewish?” “Yes,” I would answer. “Then why don’t you go to temple?” I would be nonplussed, and sort of murmur, “We don’t believe in that kind of thing.” But my “we” wasn’t genuine. I was dying to go to temple, and drank in all I heard about what it was like there. In adulthood, my brother confided similar longings to me. What you’re doing is so important, a super model for people to follow.
Vive la difference! You and your children are lucky to be descendants of Christianity – that great engine for individual development- and Judaism, which sustains us as a people and as members of the tribe. From a contrarian point of view, though: doesn’t multiculturalism and “interfidelity” require separate contributary orthodoxies to maintain the strength and integrity of its sources?
Danny the Contrarian–
I agree that sustaining the rich particularity of traditions and history requires attempting to sustain the specific form and details of the tradition and history. That is precisely why our interfaith families community teaches Hebrew literacy, and labels prayers and rituals and holidays as specifically Jewish or Christian so that children (and adults) can differentiate between the two and absorb the specific flavors of each. The alternative would be closer to a Bahai or Unitarian perspective (see my post labeled “Why Aren’t You a Unitarian?”). I would disagree that “orthodoxy” is required however. Orthodoxy (in perhaps any religion) is deeply problematic for me as a woman: the “strength” contributed by orthodoxy is offset for me by the deep flaws of fundamentalism.