Once the famous scientist Louis Pasteur (the one who discover the microorganisms and invented the process of pasteurization) was eating with some friends and grapes were served. Everyone was about to eat them when Pasteur stopped them and started explaining the necessity of washing the grapes before eating them.
While he was explaining his theory of the microorganisms, he was washing his grapes in his glass of water. His explanation was longer than the washing of grapes. So, while he was explaining he started eating his grapes. He was very enthusiastic about his explanations of the bacteria, microbe, germs, etc. But his friends started laughing because he just drank water from the glass where he washed his grapes. When he realized what he did, he started laughing as well.
When our behavior is not coherent with our teachings we make people laugh rather than make people change their behavior. This is why it is very important to be coherent with our behavior and not to nullify our teachings by our bad example.
This is particularly important for Christians. We Christians must preach the Gospel and if our behavior is not coherent with our preaching we will make people laugh rather than accept Jesus’ doctrine. We will end up doing what the scribes and the Pharisees did at Jesus’ time. In fact, Jesus warned His disciples against the scribes and the Pharisees because they taught things but did not put into practice what they taught: do and observe all things whatsoever [the scribes and the Pharisees] tell you, but do not follow their example. For they preach but they do not practice (Mt 23:3). From these words we can come to the conclusion that incoherency between our words and our behavior is something unpleasant to God.
There is another risk when we do not try to live what we preach. It is the risk of little by little changing what we preach or teach. In fact, ideologies are the result of trying to change the truth and make it match with our behavior. There is an expression that we should always remember: the one who does not live as he thinks ends up thinking as he lives.