“Secular” is, interestingly, a “church word”. It comes from Catholic theology and pertains to the fact that the Church is not a theocracy and does not see itself as competent to run everything. Human disciplines such as state, science, arts, philosophy, etc have their own own experts with their own fields of competence. The problem comes when the secular shoves the sacred out of its field off competence and tries to becom the summon bonum for all of life. When you do that, you start worshipping nature and nature worship is, for humans, always unnatural. We start, among other things, killing our young and even cannibalizing them.