The Litmus Test: For Christians Only
A litmus test is a test in which a single factor is decisive in proving the presence or absence of something. “I have eternal life,” many say, but passing the litmus test determines whether someone has truly believed as the Scriptures say.

That’s why 1 John was written; its sole purpose was that those who read it could know whether they had really received saving faith. For the Savior and the apostles knew that people could believe in vain.

Some would claim to see, even though they were blind. Their guilt couldn’t be removed. But those who didn’t claim to see, and so didn’t have the confidence that they had passed out of death into life after reading 1 John, still had an opportunity to believe and love as their Master commanded all His disciples to love — which was just as He had loved them.

The litmus test of 1 John reveals the presence or absence of the love of God. Paul wrote in Romans 5:5 that “the love of God has been poured out in our hearts by the Holy Spirit.” The book of 1 John lets anyone know (who wants to know) whether this has actually happened in his life, or whether he only has the concept of love without the power to love.

When 1 John was read to the church, those who heard it had to judge their walk according to what the apostle had written them. That is just what we have to do today when we read it: ask ourselves the question, “Do we have fellowship with one another because we walk as He walked?” They could not have fellowship with the Savior in heaven without having it with John, their apostle, as well. His letter did not persuade those who were not in fellowship with him. They continued to love the world, dispute his teachings, and ignore the needs of their brothers. Such “believers” effectively discarded First John as an “epistle of straw.”

To disregard First John as an “epistle of straw” doesn’t mean to question its inspiration, authorship, or date of composition. It means to ignore, as Martin Luther did with the Letter of James, the evidence of the litmus test 1 John gives to all who claim to believe. His sheep hear His voice and do not reason it away.

We’ve written this paper for you, the sincere ones in Christianity, because we love you and desire to see our Savior get what He deserves — what He paid for, what He died for. May His Kingdom come on the earth, just as it is in heaven.

John 7:37-39
John 9:39-41
John 13:34-35
Fellowship is in the Greek a very rich word: (#2842 from 2844); partnership, i.e. (literally) participation, or (social) intercourse, or (pecuniary, which means relating to or involving money) benefaction; (to) communicate, communication, communion, contribution, distribution, fellowship.