Recent events should show us (as well as all of human history) that secularism isn’t actually possible. Every state will always enforce its worldview. That worldview may be expressed in explicitly religious terms, or philosophical terms, or absolute loyalty to the emperor or the party, but it always comes to the same thing- whatever the ruling elites think will bring about their desired state of affairs is what they will pursue.
The wonderful thing about Christianity is that Christianity, rightly understood, does not see our hope in this age. Therefore we can be tolerant of other worldviews. Christian rulers will do what they believe they should, and that means that society is going to be structured according to Biblical norms. And we believe in those norms- history shows that it is those Biblical norms which have done the most to bring peace, prosperity, technological progress, justice and freedom on earth. But earth is not our goal, and thus we have no need to force everyone else to think as we think or to worship as we worship. That’s the Messiah’s job. He will take care of that when He returns.
In Rome at the time of Christ, the worship of the emperor was ruthlessly enforced because they perceived that the worship of the emperor was the only thing that could hold together such a vast and diverse empire. When any state’s goal is the creation of the ideal society on earth, it will always trend to the totalitarian, to controlling people as totally as they are able.
But the Christian goal is not the creation of the perfect society on earth, but the preparation of souls for eternity, when Christ will create that perfect society, and therefore we desire the winning over of hearts and minds by persuasion, not the compulsion of conformity by force. Christianity is therefore the only worldview that can truly tolerate diversity of worldviews. Christians have not always lived up to this ideal. But it is out of the Christian worldview, and only that worldview, that such ideas as religious freedom and tolerance arose. It is only in that worldview that diversity of thought can really be permitted.
The elites of our “secular” society right now is busy stamping out any deviation from the approved party line. We’ll see how far they get. But our hope is in eternity, of the glorious perfect kingdom which Christ is creating and has created, and will bring to pass when He returns. Only to Him will every knee bow and every tongue swear, and not to any earthly ruler.