A secularist state knows its place. It keeps the peace, punishes evil, maximises human flourishing and individual freedoms. It does not preach at the people. Officials do not get to write their private morality into law.
That is, dare I say, the ideal secular state. Not neutrality toward good and evil. Rather, a small state, operating for the good of its own people. It would uphold each person's right to self-expression, individualism, and choice, insofar as it does not impede another's.
What we have today, as much as the leftists and communists would say otherwise, is anything but a secular government.
Speech is criminalised, there are protected groups you can't criticise, there are surgeries performed on people that can't reasonably consent, the mass extermination of human life, schools indoctrinate children with "the science". The list could go on for paragraphs...
A government like that is actively trying to replace the role of God.
Society itself should reflect the people's spiritual state, not what the state has propagandised or forced them to believe. Worldview formation belongs at home, with families, communities and churches. Not the state, lest it replace God.
This is where Christian Nationalism falls apart, even when it often seeks the same outcomes I do. The failure is not that Christians are uniquely evil. The body count of so called secular governments are astronomically worse, don't get me wrong. The failure is the fusion. To put it bluntly, I don't want to see heretics put to death.
When the church and the sword become the same office, the church stops being the church. It starts coercing obedience with fines, censorship and death. The state stops being the state. It claims the conscience with the same tools.
That doesn't mean I advocate for open borders and gay race communism. Rather my argument is this: a government that knows its office, and exists for its own peoples flourishing and individual freedoms, would simply not allow abortion or mass unchecked immigration from the third world.
Abortion is the killing of a child, the snuffing out of a life that could have been. Calling it healthcare does not change that. A rational secular government would deem this as infringing upon the rights of another individuals right to life.
Mass immigration treats the people as interchangeable economic units. Except culture and a people isn't something you can just swap out to make the GDP go brrr. There are measurable costs that we are all feeling right now: housing, hospitals, schools, jobs, wages, and trust. How is that working to maximise human flourishing or individual freedoms when the people the state exists for are being betrayed at every turn?
The cost they will not name is us, the people. Mass immigration replaces the native population and abortion kills the next generation before it arrives. The state exists for its own people, not the world.
Christian rule, if it ever comes, will only ever be a byproduct of the Gospel, not a substitute for it. Nations rise and fall as God judges them. The state's job is smaller than that. Keep the peace, guard its people and leave the conscience to God.