Western culture was built on Christian culture, so it cannot exist without it, yet that is what we are trying to do. We are trying to eat the fruits of Christian culture while leaving Christian faith and values behind.
For many centuries, the church was the culture maker. Christianity was the dominant faith, and the normal worldview. Clergy giving their weekly sermon were the main cultural voice. They explained how the world and works, and how we should live. That situation changed a couple of centuries ago, and the Christian voice is just one small voice, lost in the hubbub of the world.
In modern culture, the main cultural voice is the arts and entertainment media. We learn how the world works from them. The media teach us what to believe, and what to do, but they do not mention God. They tell us how to live. Have a good time. The media now shape our culture.
The first step to restoration is proclaiming the gospel, but bringing people to faith will not be enough. God will need to raise up prophetic culture makers, who voice is so sharp and clear that it rises above the clamour of the media.