In our church's youth ministry, most of the school year is built around Bible study and small groups rather than traditional sermons. (On Sunday mornings, the youth group worships corporately with the rest of the church, not in their own service; so they get their sermons, don't worry!)
But during the last two summers, we have done topics on apologetics, which you can see here.
Why do we do this? Very simple: we live in the most aggressively atheistic society in the history of the world.
Don't take this lightly: some studies show as many as 60% of regular youth group attendees in Protestant churches will leave church during their college years. Many will never return. Atheism--which really began to rise in the West after the Enllightenment--remained a small percentage of the population for a long time. But now, it is quite popular.
The New Atheists like Sam Harris, Penn Gillette, and Richard Dawkins are actively evangelizing, in attempts to create a movement. They are not satisfied to disbelieve in God; they rather believe they have a mission to "fix" those who disagree with them.
Don't believe me? Think that only people overseas are really struggling in their pursuit of Christ? Read stories like this one, from the New York Times a few months back: in Louisiana they have actually started an atheist church to make it easier for people to transition from Christianity to atheism. That way they can get together and sing, hear a sermon...just without God. In fact, specifically anti-God.
I've written before about how some Christians complain about their suffering, when the government calls Christmas trees "holiday trees"; this kind of first-world problem seems absurd to me when Christians overseas are having churches bombed.
However, that is not to say we do not have our struggle in our culture today! We definitely do. We may not be physically at risk, but--much like early Christians in Rome or Greece--we are under massive intellectual attack. The Western Church is dying. In the Middle East and Asia and Africa people physically oppose Christianity, but they too believe that there is a spiritual reality. Here in the West, we have a danger which is no less real, just more insidiously subtle: our culture simply believes that there is no God.
Our kids are surrounded by the message--once subtle, now overt--that: (1) intelligence is the highest virtue, and (2) all intelligent people are atheists. Neither of those two is true, but it is shared so widely that it becomes assumed.
Our brothers and sisters overseas are physically attacked for their beliefs: we are spiritually attacked for our beliefs. Both are legitimate and powerful and dangerous.
Do not be idle, parents. Do not allow your children to go into the battle blindly. Arm them with truth, with righteousness, and with faith. Teach them--as 1 Peter 3:15 says, always be prepared to give an answer to those who see the hope within you.