A semi-truck barreling towards us is an easy cue for us to get out of the way or we will suffer major loss. However, smaller things that we may not see approaching us; or worse, something we may think is harmless can be our undoing. Allowing that ‘small thing’ that doesn’t fit with the purposes of God to infiltrate our lives and our faith is detrimental! Paul uses the metaphor of a little yeast working through the whole batch of dough. We will look at the importance of guarding our hearts and minds and establishing boundaries to prevent this from happening.