Trust and Obey
The KISS principle—Keep It Simple, Stupid—is itself a rather simple principle. It argues that when we find ourselves entangled in complex and complicated arguments, chances are we have already left the proper playing field. While, for instance, the gospel is a glory that can be studied and expounded upon for a lifetime of lifetimes, we nevertheless confess that something has gone wrong if we cannot rejoice in our salvation simply by confessing, “Lord be merciful to me, a sinner.” Jesus said that the man who prayed that way went home justified (Luke 18:14).
The same is true after our souls are saved. Our forgiveness, our justification, our adoption all flow out of a glorious but simple truth that while we were yet sinners Christ died for us (Rom. 5:8). Our sanctification, however, our calling to grow in grace and wisdom, to put to death the old man, to become more like Jesus—this is simple too. There is no great and deep secret—we are called to trust and obey.