We’ve been going through Paul’s letter to the Philippians in our Kindred series, and there is a little section from the second chapter of that letter that has played an important role in my pursuit of godliness this year: “Do all things without grumbling or disputing, that you may be blameless and innocent, children of God without blemish in the midst of a crooked and twisted generation, among whom you shine as lights in the world, holding fast to the word of life” (Philippians 2:14-16).

Dozens of times in Scripture we are warned against complaining. One of my own goals this year has been to stop grumbling, especially at work among my colleagues. Jesus’ words about the connection between the heart and the mouth have helped me: “out of the abundance of the heart the mouth speaks.” So, when a venomous complaint comes out of my mouth, it means there is something toxic in my heart.

If you’re like me, you have a dozen excuses to explain why your grumbling isn’t sinful. But these rationalizations are nothing more than air fresheners in a smelly car. My car stinks because a container of leftovers has been rotting there for three days. The solution isn’t to hang an air freshener or roll windows down. The solution is to get the trash out of my car—that is, out of my heart. Something rotten in my heart—such as pride, resentment, entitlement, envy, bitterness—is fuming out of my mouth when I mutter and complain.

My complaining isn’t merely a heart problem before God, it’s also a community contaminant. Those riding in my car have to put up with the odor of my rotting pride or decaying bitterness. So, what I’ve tried to do this semester is to stop justifying or playing down my complaining and start repenting of the sin in my heart, which is the source of my muttering.

It’s good to stop my mouth when I feel grumbling bubbling up, and I think I’ve improved with that a bit. But, since complaints are stenches that should alert us to the need to clean out some heart-trash, it’s even better to replace the pride in my heart with humility; replace the envy in my heart with contentment; replace the fear in my heart with love. And that takes the work of God in my life. May the words of our mouths and the meditations of our hearts be pleasing to our Father.