There are people who claim to be experts at reading body language. They can discern what is being communicated in the ways others position their bodies and hands and by the facial expressions they make. This could be a useful skill, especially for knowing—or at least coming close to knowing—whether someone is being genuine or false.

There are ways, though, that Christians can conduct themselves with inauthenticity that cannot be read by people fluent in body language. It’s a sad fact that different motivations drive people to serve in the name of Christ. Some people serve not out of genuine interest in the well-being of others but with self-interest leading the way. They may want to be noticed. They may crave a pat on the back. They may be pursuing a good reputation. Such a motivation may lead to good things being done, but it doesn’t produce genuine service. Christian service, in other words, can be fake. From a distance, it looks like the real thing, but get up close and you find it to be wanting.

So how do we know what is authentic? Here are two signs of a genuine heart of service for us to look for in ourselves, as well as in others.

First is the willingness to serve in anonymity. This is the kind of service that delights in doing good regardless of any attention. “Among those born of women none is greater than John,” said Jesus Himself (Luke 7:28)—and yet the Baptist longed to see Christ glorified at his own expense, a passion articulated so memorably when he confessed, “He must increase, but I must decrease.”

Second is the existence of sincerity. The apostle Paul affirmed that his friend Timothy, for example, was “genuinely concerned” for the Philippians’ welfare, unlike those who “seek their own interests” (Philippians 2:20-21). Epaphroditus, too, was “longing for” the good of the Philippian church (v 26). Such longing cannot be faked but arises out of genuine love.

Many years ago, one preacher declared that he was “content to be God’s errand boy.” Could you say that with integrity? Do you delight in decreasing if that means Christ’s glory will increase? Do you have real concern—longing, even—for the good of others? Those around us may not be able to tell what motivates us, but we can be sure that the Savior we claim to serve most certainly can.

Perhaps this is a good opportunity to prayerfully consider the example of Paul, who said, “I do not account my life of any value nor as precious to myself, if only I may finish my course and the ministry that I received from the Lord Jesus” (Acts 20:24). Ask God for the grace to echo these words with sincerity. Who knows what He might do with a life that you have fully surrendered to Him?