John said, “I have no greater joy than to hear that my children walk in truth” (3 John 1:4). Holy conduct will bring genuine joy. John rejoiced that many of his converts were walking a holy life and his rejoicing gives us two good lessons.
First, the source of joy. Every parent who has sent a child to school knows what a delight it is to hear that his or her child is honest and well-behaved. In some ways, honesty, promptness, courtesy, and respect for authority are just as important as grades. Happiness comes from holiness (Matthew 5:8). Sin says happiness comes from sinning not saintliness. But as every sinner soon learns, that is a Devil’s lie.
Second, the stigma of truth. If you want to be happy you walk in the truth. None of us likes to be demoted and forsaken, but walking in the truth is not popular. Hardly anyone will help or encourage you. Sometimes even Christians are no help with walking in the truth because too many try to live a double life. Walking in the truth can be very dividing. If you want to be upright, many of your friends will part company with you (2 Timothy 4:10).
In short, holiness costs! It will cost you friends, positions, and possessions — but not real joy.
via University church of Christ