The term ‘secular’ is best understood by looking at the ‘eonic effect’, and the modern transformation. Then the mistake of confusing it with scientism will be clear. That science can’t fully define modernity should be common knowledge: many key figures from Rousseau to Kant warned here, but the lesson was totally lost on scientists, whose views are already archaic.
Note that science can’t even handle the idea of freedom, on which the rise of modern liberalism depends. That should be a warning not to confuse modernity and science ideology. Kant patiently reviewed the whole question at endless length, yet most scientists have never read him, and never would read him, or anyone not in the narrow range of their belief system.
A reverse confusion is also rampant: the critics of modernity point to scientism and use its domination as an excuse for a postmodern anti-modernism, and/or renewed traditionalism. But the rise of the modern, as we have noted, is not the same as the rise of scientism.
A careful study of the rise of the modern in WHEE (online starting with the link above) is highly recommended to resist the idiocy factor being promoted by science fanatics who have lost the balance needed to really deal with the question, or with religion.