As long as you keep your mouth closed, I told myself, you won’t be doing anything wrong. I’d been outwardly holding back my anger toward a colleague after misinterpreting things she’d said. Since we had to see each other every day, I decided to limit communication to only what was necessary (and retaliate with my silent treatment). How could a quiet demeanor be wrong?

Jesus, however, said that sin begins in the heart (Matthew 15:18−20). My silence may have fooled people into thinking all was well, but it wasn’t fooling God. He knew I was hiding a heart filled with anger. I was like the Pharisees─“who gave honor with their lips, but their hearts [were] far from [God]” (v. 8). Even though my outward appearance didn’t show my true feelings, the bitterness was festering inside me. The joy and closeness I’d always felt with my heavenly Father were gone. Nurturing and hiding sin does that.

By God’s grace, I told my colleague how I was feeling and apologized. She graciously forgave me and, eventually, we became good friends. “Out of the heart come evil thoughts” (v. 19). Jesus says that the state of our heart matters because evil residing there can overflow into our lives. Both our exterior and interior matter.