Growing in both grace and truth acts as a guardrail on the narrow road of following Jesus (Mark 8:14-21). Jesus warns His followers to watch out for the yeast of the Pharisees and that of Herod (Mark 8:15). Jesus is saying that there are small, subtle yet sinful ideas and beliefs that can carry significant influence in our hearts and run us off the narrow road that leads to life. The yeast of Herod represents the idea that we get to decide what is true for us. It minimizes or even rejects God’s truth. It dismisses temptation and sin, and anyone who calls out sin is being judgmental. The yeast of the Pharisees emphasizes external rules and behaviors. It looks down on others in pride, which ultimately leads to hypocrisy. Walking in both grace and truth guard against either of these extremes. Those growing in grace and truth know God as holy and forgiving, hate sin immensely and love people radically, and want to be like Jesus and know it can only happen by God’s power at work in them.