We live in a world of sharp distinctions. Very few are concerned about you and your private religion. They are concerned about what you do in public. The vast majority of folk draw a clear line between the sacred and the secular ... even Christians.
What we do in church is sacred; what we do at work is secular. Reading our Bibles is sacred; reading the latest news is secular. Listening to Christian music or Christian preachers is sacred; listening to the latest pop singer is secular. It isn't a matter of debate. Instead, it's a matter of principle. While we've swallowed wholesale "the separation of Church and State", we've also embraced the separation of religion and everyday living.
It's in this dichotomy that self-professed Christians find themselves able to defend abortion or indulge in sexual sin or the like while going to church on Sunday all smiles and piety. We can be holy at church. That's sacred. Secular is something else.
As would be expected, however, while the distinction appears to be quite sharp, it turns out that one must necessarily invade the other. So while "church is sacred" and "the rest of life is secular" works for awhile, what happens when the sacred attempts to encroach on the secular? What happens when the preacher, for instance, says that homosexual behavior is a sin? Oh, now we've gone too far. What has church to do with homosexual behavior?
When the sacred collides with the secular, a winner must be declared. When Scripture speaks of "But I want you to understand that the head of every man is Christ, the head of a wife is her husband, and the head of Christ is God" (1 Cor 11:3) or "Wives, submit to your own husbands, as to the Lord" (Eph 5:22) and the secular demands full equality (by which they mean "the same"), the Christian must decide "Do I go with the sacred or the secular? Do I side with Scripture or with my culture?" And, of course, generally speaking the secular will win out. "The Bible can't mean that because our society tells us otherwise."
I would argue, however, that this is a false dichotomy. I would suggest that we Christians have bought a lie. While our culture tells us to keep our religion out of the public square, our God tells us, "Whatever you do, do all to the glory of God." (1 Cor 10:31) We tend to focus on the spiritual as if that's "something else", Paul tells us "Whatever you do, in word or deed, do everything in the name of the Lord Jesus, giving thanks to God the Father through Him." (Col 3:17) Biblically, "business" and "church" are both in the realm of "sacred".
According to Scripture, Christ is Lord over all (Acts 10:36; Rom 10:12). All things are for Him (Rom 11:36). There is no such thing as "sacred versus secular" in God's view. We don't get to make that distinction. That means that every secular thing we do is sacred; we do it with His guidance by His power for His glory. From preaching the Word to tying your shoe, we are to do all things for Him. There is no "secular" for the Christian. Only that which we do for the Lord and ... sin.