The Collision Course of Christian Exclusivity
What has changed over my lifetime is the self-consciousness of Leftists and secularists and Cultural Marxists. The classically liberal society, which was shaped by Protestant Christianity and which prevailed since the U. S. Founding, permits political and religious liberty. Christians are happy with this arrangement (should insist on it, in fact), because if left politically unmolested, Christianity, by the Holy Spirit’s power, can peacefully vanquish all rivals. When you have the power of the Spirit, you don’t need the power of politics to defeat your religious opponents.
But secularists lack this power, and they are increasingly aware that classical liberalism (see “Liberals and Conservatives Against the Free World”) works in favor of Christianity and in the sort of ordered, virtuous society that Christianity tends to foster.
J.I. Packer's article (PDF)
Why I Walked
Sometimes loving a denomination requires you to fight
By J.I. Packer