Matthew 15: 18
But the things that come out of the mouth come from the heart, and those things defile the person.
Matthew 12:34
You offspring of vipers, how can you, being evil, express any good things? For the mouth speaks from that which fills the heart.
Jesus said that in the last days, wolves would come dressed as sheep so we must be adept at discerning who is of the truth and who is not. Jesus said you would know the wolves (and the sheep) by their fruit. Yesterday, I sent you the test. It comes out of Colossians 3 and Galatians 5. Here is another way to tell the difference between those who say they follow Jesus from those who actually do. Check the fruit of their mouth.
No one who is of Christ lies. Period. End of story. Does that mean if a person ever tells one lie they are devil spawn? No. It means they relaxed their guard for a moment, perhaps have not been spending enough time with the Lord. However, a habitual liar or one who doesn’t have a strong relationship with the truth is not a Christ disciple. I’ve said it before, lying comes from the devil’s house. You can’t dance to his tune and be in harmony with Jesus.
Other language will give one away too. Is the person’s language kind, gentle, peaceful, patient, filled with goodness and faith? Or are their words harsh, critical, and judgmental. You can tell what is in a person’s heart by what comes out of their mouths.