What goes into someone’s mouth does not defile them, but what comes out of their mouth, that is what defiles them.”
But the things that come out of a person’s mouth come from the heart, and these defile them. For out of the heart come evil thoughts—murder, adultery, sexual immorality, theft, false testimony, slander.
In the Jewish customs of that time, cleanliness and godliness went hand in hand. But, if external purity matters, how much more does internal purity matter? Bryan Chapell writes that “few things are more spiritually harmful than the outward practice of religion apart from the repentance and faith that characterise the true follower of Christ”. We work hard to keep our outward actions and appearance attractive, but what is in our hearts is more important. Others cannot see into our hearts, but God can.
Jesus challenges the hearers and us about our heart condition. What does our thought life reflect? Rather startling sins are included alongside murder and adultery, like slander and false testimony (verse 19). How often do we say unkind words about someone else? How easily do we share something about someone as a prayer request? How often do we exaggerate and embellish, or understate the truth?
Warren Wiersbe writes, that “we must constantly remind ourselves that true religion comes from the heart. We love from the heart (Matthew 22:37), obey from the heart (Romans 6:17), give from the heart (2 Corinthians 9:7) and pray from the heart (Psalm 51:10,17).”
Let us pray and ask God to guard our hearts from evil thought, and repent of any sins that we have commited, and ask Him to create in us a clean heart.