I'm just going to camp out on this one verse today because I'm fascinated by it. Jesus warns against practicing our Christian piety for the sake of being seen by others, because when we seek the praise of others we are glorifying ourselves. He says God only rewards the service that we do for his praise alone.
In evangelical Christianity today I do hear hints of this teaching. I hear warnings against being like the "Sunday only" Christian who is pious at church but lives like a heathen the other six days of the week. I hear exhortations to examine our motives and make sure we aren't serving at church for selfish, self-glorifying reasons. I know we aren't supposed to get puffed up with pride when others praise us, and some Christians make it a practice to immediately respond, "Praise God!" in effort to deflect the glory heavenward when they are complimented.
But here I think Jesus is going much further and talking about practicing a secret piety that no one knows about and no one ever sees. We criticize the "Sunday only" Christian because he goes to work during the week and is a bad witness to his co-workers. But Jesus is talking about how you behave when even your co-workers aren't looking, when they are not even around to notice what a good Christian example you are and say to themselves, "Hey, he/she really does walk the walk." Or take the Christian who serves at church. It's not just about deflecting the praise of others heavenward when they see your dedication. It's about not getting any praise at all because much of the service you render is never seen.
Maybe it's just my imagination, but I don't think we're all that comfortable with the idea of encouraging secret piety. The most popular catch phrases in the church today run against the grain of Jesus' exhortation to "beware of practicing your righteousness before men." For instance, we're always told to "be an example." That's showing other Christians how to live. Or we have to "be a witness." That's showing non-Christians who Jesus is. We also have to "be accountable." That means disclosing aspects of our personal lives to fellow Christians. And we mustn't forget to "be involved." That means doing service alongside other Christians. None of this is bad, in fact all of it is for a good purpose. Except that when you put all these exhortations together, they drive you along a current that runs in an altogether different direction than what Jesus is saying, which is that God most values the things we do that are seen by his eyes alone.
Most of the time when we talk about "the things we do in secret," we are referring to wicked thoughts and secret sins. I wonder how healthy that is, especially since Jesus reminds us that there is also such thing as secret prayers and secret charity. He certainly has a more optimistic view of his people's inner lives than we do of ourselves. Maybe we don't need to smother ourselves with endless activities and accountability and instead we should do more to trust the secret work of God in our lives. The Holy Spirit might more effectively speak to our hearts if only we'd leave each other alone for a change and go off to some quiet place to listen.