First off, what does the Bible say about serving two masters? Wait, you may say, this has nothing to do with serving two masters! But it does, you cannot serve a secular humanist ideal and God at the same time. Secularism at its core IS Humanism. Now, to what the Bible has to say on this matter, Matthew 6:24: “No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon.”
Now, Secularism came out of the 1800s during the zenith of the enlightenment. For those who are fuzzy on what the enlightenment entailed, this name is given to the era that elevated the notion of Reason, either God's or Man's. The European Enlightenment focused on Man's Reason, while the United States focused primarily on the notion of God's Reason. In the 20th Century, the Christian Enlightenment sent men to the Moon, and missionaries and aid to the nations. The Secular Enlightenment sent Jews to the ovens and dissidents to the gulags. We also have the Secular Enlightenment to thank for “Critical Theory”, Utilitarianism (modern prisons), Marxism, Nazism, Facsism, Stalinism, and more.
Some Questions from each avenue of thought:
Theology: Was Jesus a Secularist? What does the Bible say about religion and politics? Well, first off, please note that the Sanhedrin was the political leadership of Christ's time. While Christ did not start a Maccabean revolt, Christ also was not silent on the issues of the day. He regularly sparred with the Sadducee faction that was the majority seat holder in the Sanhedrin. Paul also played politics when he pitted the two parties against each other in Acts 23:6.
“But when Paul perceived that the one part were Sadducees, and the other Pharisees, he cried out in the council, Men and brethren, I am a Pharisee, the son of a Pharisee: of the hope and resurrection of the dead I am called in question.”
Christ spoke of overbearing taxes in Matthew 17:24-27
“24 And when they were come to Capernaum, they that received tribute money came to Peter, and said, Doth not your master pay tribute?
25 He saith, Yes. And when he was come into the house, Jesus prevented him, saying, What thinkest thou, Simon? of whom do the kings of the earth take custom or tribute? of their own children, or of strangers?
26 Peter saith unto him, Of strangers. Jesus saith unto him, Then are the children free.
27 Notwithstanding, lest we should offend them, go thou to the sea, and cast an hook, and take up the fish that first cometh up; and when thou hast opened his mouth, thou shalt find a piece of money: that take, and give unto them for me and thee.
and in Matthew 22:20-22
20 And he saith unto them, Whose is this image and superscription?
21 They say unto him, Caesar's. Then saith he unto them, Render therefore unto Caesar the things which are Caesar's; and unto God the things that are God's.
22 When they had heard these words, they marvelled, and left him, and went their way.”
In context, both of these have different meanings, but neither of them support the idea that Christ was some how a Secular Humanist who believed that the man made state was in a moral authority above God's. Rather instead these verse support the doctrinal principle that Christ was answering each situation in a way that furthered the Gospel.
Peter and the Apostles retorted to arrest by the Sanhedrin in Acts 5:29:
“We ought to obey God rather than men?”
This along with the Standard of Romans 13:1-7 set a rubric for the Christian to follow:
“13 Let every soul be subject unto the higher powers. For there is no power but of God: the powers that be are ordained of God.
2 Whosoever therefore resisteth the power, resisteth the ordinance of God: and they that resist shall receive to themselves damnation.
3 For rulers are not a terror to good works, but to the evil. Wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same:
4 For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil.
5 Wherefore ye must needs be subject, not only for wrath, but also for conscience sake.
6 For for this cause pay ye tribute also: for they are God's ministers, attending continually upon this very thing.
7 Render therefore to all their dues: tribute to whom tribute is due; custom to whom custom; fear to whom fear; honour to whom honour.”
From the Chair of Philosophy one must ask can the worship of Man's Wisdom coexist with a submission to God's Wisdom? 1 Corinthians 3:19 says:
“For the wisdom of this world is foolishness with God. For it is written, He taketh the wise in their own craftiness. “
Remember why they want you to live a Secularist life: If you're silent about your beliefs, then they are free to espouse theirs. Secular Humanism is almost an oxymoron in this one point: It is a religious conviction. Now, Man may be God, effectively, in their religion, but this does not make this any less of a faith statement.
On the note Culture, what kind of Culture does a Secularist Christian create?
Pew Research shows us the aftermath of a society that is inhabited by Secular Christians: https://www.pewresearch.org/religion/2019/10/17/in-u-s-decline-of-christianity-continues-at-rapid-pace/
The further we get away from an outwardly Christian lifestyle, the further our culture slides. Christ said that we were to be the Salt and Light. In Matthew 5:13 it says: “Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted? it is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men.”
From the Economic side of things, we should note that we only have so much time on this Earth. What are we valuing when we choose to live a life that is devoid of Christ in public. Some Christians fall into the trap of a false sincerity, this is not what I'm referring to. We need to be about the business of discipling. Are we not bought with a price? We must be prepared to die for Christ, let alone be discomforted.
We are bought with the blood of Christ, too precious of a price to waste our lives being secular. They aren't afraid to speak of their religion, why should we be? Simply maintain a Christ like tenor in a bold Daniel like lifestyle and the Holy Spirit can bring revival.