Among secularists, the term ‘humanist’ is a good sign. I belong to a community of secular humanists (although it doesn't have enough families to help with raising children yet).

You can get a close copy of mainline Protestant church socialisation at a Unitarian Universalist congregation in the United States. (Individual congregations vary widely, however, and not all are really secular, with various degrees of monotheism, neopaganism, and pantheism all possible in the culture, although they should be accepting of anybody.)