My answer is Augustinian in nature. Desire is primary.
We tend to assume that evangelism is about intellectual assent, an attempt to convince people of a truth. Or even a submission to the truth. I've heard way too many Boomers describe the problem with young people as rebellion and disobedience.
The deeper problem, though, is desire. As Augustine described, love moves the intellect and the will. Love is the arena of evangelistic action. This means that, first and foremost, we have to evoke a desire for God.
The trouble, though, is obvious. The Christianity on display before our young people isn't remotely attractive or compelling. Christianity seems to them small, anxious, preachy, ugly and mean. Christianity is repellant. And unless you deal with that visceral distaste all your evangelistic efforts will fail. As I said, desire is primary.
So, that is my advice for churches. Your young people need to see a compelling Christian witness. They don't need to hear a sermon or a lecture from you. They don't need your finger-wagging or concern-trolling. They need to see something that evokes in them a desire for God. Something they see as true, beautiful and good. Because if all they see in our pews and social media feeds is culture-warring, fear-mongering, mean-spiritedness, and over-politicization, well, our young people will head for the doors. Ugliness does that. It causes you to walk way.
As Dostoevsky said, beauty will save the world. So let me say it again.