An important lesson that a communicator must never forget is that your preaching/teaching is never done in a vacuum.
For example, whatever you are going to say this Sunday you must connect it in some way to the terrible tragedy that occurred in Boston this week. All week long your people have been inundated with news about the bombing and the follow up events. To fail to mention this and apply Biblical truth to those events will communicate loudly that what you have to say does not matter in the “real world” (i.e. their own world).
This does not mean that you preach/teach the headlines, what it means is that occasionally there are events that are so riveting to your congregation or class that to fail to acknowledge those events is to fail to minister to your people.
This leads me also to another important point: give your people hope.
Ever how you respond to the Boston bombing (and also the explosion at the fertilizer factory in Texas) don’t turn it into a diatribe against Islam or the sorry state of young people today or how this is to be expected when a nation turns from God, etc.
There may be some truth in what you say but that does nothing to minister to the aftershock that is in your people’s own lives. Remember some of them have had “explosions” in their lives this week that have left them mangled and mutilated. Cursing the darkness is not going to help them now that the explosion has occurred.
What I’d suggest is to remind them of the sovereignty of God and how ultimately He is working all things together for our good. Remind them of Moses’ words as the people trembled with doubt and fear in knowing that he was soon to die and they would be leaderless. Moses reminded them:
27 The eternal God is your refuge,
And underneath are the everlasting arms;
Deuteronomy 33:27 (NKJV)
In summary: There will be an occasion that something occurs that is so significant that you must adapt what you are going to say to address that occurrence. To fail to do so is paramount to telling your people who you are out of touch with their lives. Furthermore, the way you should respond is to give your people hope.
Like the prophets of old, warn before the tragedy, but comfort afterwards.