The truth is there isn’t a single person in this world that can escape the temptation to lie. In Jesus’ most famous sermon, He demands that every Christian pursue radical truthfulness in speech. According to Jesus, if you’re one of His true followers, your life will be characterized by truthful speech.
Christians ought to reflect the life of our Lord Jesus Christ. That means more than just external conformity to His words. In the Sermon on the Mount, Jesus teaches that you must obey His words from the heart—including your speech.
In the Sermon on the Mount, Jesus calls His disciples to a higher standard of living, one that pursues a greater righteousness than the Pharisees’ hypocritical righteousness. Christ teaches you that if you’re His disciple, you must be characterized by speaking truthfully, including making oaths and vows.
Although Jesus commands His disciples to be committed to radical truthfulness, this does not mean that Christians should do this in an unbiblical manner. Scripture contains several warnings signs that believers should be aware of in order to avoid committing other sins while speaking truthfully.