Using an iterative algorithm to solve a computational problem is a bit like following a road, possibly long and difficult, from your start location to your destination. With each iteration, you have a method that takes you a single step closer. To ensure that you move forward, you need to have a measure of progress telling you how far you are either from your starting location or from your destination. You cannot expect to know exactly where the algorithm will go, so you need to expect some weaving and winding. On the other hand, you do not want to have to know how to handle every ditch and dead end in the world. A compromise between these two is to have a loop invariant, which defines a road (or region) that you may not leave. As you travel, worry about one step at a time. You must know how to get onto the road from any location. From every place along the road, you must know what actions you will take in order to step forward while not leaving the road. Finally, when sufficient progress has been made along the road, you must know how to exit and reach your destination in a reasonable amount of time.Our iterative algorithm is the basis for the decisions we make when backed into a corner. Sometimes, we can find strength in our rational minds to make a wise decision—but it is not often. Often, what happens is that we fall into our habits. We act out of character. It is then that integrity matters. When the fire heats up and the pressure is on, our true selves are revealed. The inner workings of our own personal algorithms come out.
Our measure of progress is the fruit of the Spirit—love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control. This is how we know that we are getting nearer to our goal. That we haven't strayed or walked in the wrong direction. This is how we know that our faith is really working. That faith isn't a mere abstraction or philosophic orientation, but a real, transformative power in our lives.
Our loop invariant is God's Word. It is how we stay grounded. How we know that we aren't merely rationalizing our actions or making decisions because of desire. God's Word is a mirror—it tells us who we really are. You cannot read the Word seriously and effectively without your understanding of yourself and the world surrounding you being transformed by its mere touch, by its penetrating gaze. God's Word remains steadfast and stable amidst all of the challenges and circumstances that we might come to face. And we can always turn to Him when we feel lost and alone because He is always there for us, to guide us and lead us home.