There’s not many tasks in life less delectable than changing dirty diapers – yet in seemingly mundane tasks such as this, through His subjects, Christ battles the devil and extends His Kingdom.
Our good works as Christians are always tainted by sin, but since they are done in Christ, they are made perfect. As Philip Melanchthon says in Article V of the Apology to the Augsburg Confession (paragraph 68),
Yet, because of Christ, they are holy, divine works, sacrifices, and acts belonging to the rule of Christ, who in this way displays His kingdom before this world. For in these works He sanctifies hearts and represses the devil. In order to retain the Gospel among people, He openly sets the confession of saints against the kingdom of the devil and, in our weakness, declares His power.
You may not get many kudos from your coworkers for taking out the trash, yet in these simple acts you serve your neighbor, confess the faith, and praise God. When you do these ordinary tasks, Satan loses ground on the plain of spiritual battle, pointing to the final consummation of all things when Christ will return in glory. As Master Philip says, “These deeds are holy works and true sacrifices acceptable to God.”
71  We think this way also about every good work in the humblest callings and in private affairs. Through these works Christ celebrates His victory over the devil, just as the distribution of alms by the Corinthians (1 Corinthians 16:1) was a holy work, a sacrifice and battle of Christ against the devil, who labors so that nothing may be done to praise God. 72  To demean such works (the confession of doctrine, sufferings, works of love, suppression of the flesh) would be to demean the outward rule of Christ’s kingdom among people.
It is a great comfort to know that in the midst of our daily toil, there is Christ with us, proclaiming His victory in the seemingly insignificant, thwarting the devil and the naysayers of this world, proclaiming His victory and ultimate triumph over evil. Changing that diaper never looked so good!
Quotes from Concordia: The Lutheran Confessions, Edited by Paul Timothy McCain (St. Louis: CPH, 2005), 110.