A life that is faithfully following Jesus provides an example for others to follow. To be a good teacher, whether you are paid to be one or one by default (such as a parent), requires you to be knowledgeable about what you are teaching and demonstrate how that teaching looks in real life. We need examples to help us move from theory to reality.
The Pharisees where the religious teachers of Jesus’ day. They interpreted Scripture for the people and taught them how it applied to their lives. Yet they missed a key component in their teaching: they didn’t live it out in their lives. It was at this point that Jesus confronts them.
1 Then Jesus said to the crowds and to his disciples, 2 "The experts in the law and the Pharisees sit on Moses' seat. 3 Therefore pay attention to what they tell you and do it. But do not do what they do, for they do not practice what they teach. 4 They tie up heavy loads, hard to carry, and put them on men's shoulders, but they themselves are not willing even to lift a finger to move them (Matthew 23:1-4; NET).
The underlying theology that the Pharisees taught was okay, but the mistake they made was burdening the people with laws upon laws on how they were to be faithful instead of providing them with an example of what faithful living looked like. Jesus doesn’t tell the crowd that the Pharisees had bad theology, but that they had bad faith. Jesus urges the crowd to listen to the Pharisees teaching, but discourages them from following their example.
We need to keep in mind that there are two parts to effective teaching: relating ideas and letting those ideas be seen in your life. When our lives do not reflect the Truth of the Gospel people will wonder whether or not it is really the truth. The best evidence for the truth of the Gospel of Jesus Christ are the faithful lives lived by His followers. When we live faithful lives we make real the teachings of Jesus. Without our example Jesus’ teachings remain simply a theory, a nice way to live.
Having the truth doesn’t do us or anybody else any good if we don’t apply that truth to our lives. The life of faith is the life that is lived based on the truth that we know. It also becomes an example for other people to follow because it is at this point that we truly become lights to the world.