Slope = Rise/Run
The slope represents our growth in Jesus. As we walk toward God, we are headed toward God and it is a positive slope. If we are disobeying Him we are headed away from Him and in a negative slope. If we are not growing at all we have a zero slope. If it is impossible to go further then it is an undefined slope.
Remember the slope is rise over run.
Jesus rose from the grave so we could run the race.
...Let us run the race with perseverance the race marked out for us, fixing our eyes on Jesus, the pioneer and perfecter of our faith.... Hebrews 12:1b-2a