Litmus tests tell you the pH level of a chemical, and that helps you identify the chemical. The term "litmus test" can be used metaphorically to describe something that is definitely not litmus paper but can similarly help you determine something. In last week's sermon, we learned that sin - particularly unrepentant, continual sin - is a litmus test that shows that a person is not really a Christian. In this week's sermon, we see that the Apostle John also gives us another litmus test: love. We can tell if a person truly belongs to Christ by their love. If there is no love, then the person is not redeemed.