34 "You brood of vipers, how can you bring evil speak what is good? For the mouth speaks out of that which fills the heart.
35 "The good man brings out of his good treasure what is good; and the evil man brings out of his evil treasure what is evil.
36 "But I tell you that every careless word that people speak, they shall give an accounting for it in the day of judgement.
37 "For by your words you will be justified, and by your words you will be condemned. (Matt 12:33-37 NASB)
Jesus, in His rebuke of the Pharisees, sets forth an important principle which is just as valid for us today as it was for the people in Jesus' day. We can claim to be godly, to even be a Christian, but the truth of our salvation will be ultimately be shown by our actions. In this case it is our speech which either confirms or denies our faith.
What Jesus says here is true. A tree is known by the fruit it produces. Years ago we had an apple tree that produced wormy apples. We tried various things to fix this, but after a few years we cut it down and started over with a couple of new ones. It was an infested tree; it was no good, and the bad fruit was the proof.
Consider two individuals who both claim to be Christians. One of them speaks kindly of others, does not tell dirty jokes and use foul language. He avoids slandering others and is always truthful. The other one curses, is vulgar, and quite often seeks to make others look bad, even if he has to lie to do it. Whose faith is real? According to Jesus the mouth speaks out of the overflow of the heart. An evil person cannot speak what is good. It is sobering to consider that our words either justify or condemn us.
In his letter to the Ephesians the apostle Paul writes this,
29 Let no unwholesome word proceed from your mouth, but only such a word as is good for edification according to the need of the moment, so that it will give grace to those who hear.
30 Do not grieve the Holy Spirit of God, by whom you are sealed for the day of redemption.
31 Let all bitterness and wrath and anger and clamor and slander be put away from you, along with malice.
32 Be kind to one another, tender-hearted, forgiving each other, just as God in Christ has also forgiven you. ( Ephesians 4:29-32 NASB)
We must guard our mouths! Our purpose is to build others up, not tear them down. We grieve the Holy Spirit when we speak out in anger or hatred, or when we slander someone else. Of course there are times when we need to be honest with someone who is in error, or perhaps has fallen into sin, but we must be careful to speak the truth in love (Ephesians 4:15) instead of in a judgemental way. The point is to give grace to those to whom we are speaking with.
So much of what we hear in everyday talk is evil. From dirty jokes and profanity laced tirades to juicy gossip and outright slander, what we are hearing tends to drag us down. I know it often grieves me, and the passage above affirms that it grieves the Holy Spirit. I understand that the world talks like this, this is what Jesus said comes out of their hearts. But to hear this from a professing Christian should not be. Let us all be careful to guard our hearts, and then our speech will be right also. One day we will answer for it.