In my discussion about the plan of salvation with a Church of Christ minister, we came across 1 John 5:13. I believe this verse teaches that if you believe on Christ for salvation that you can KNOW that you have eternal life, but he said: “IF John has written to them the same 1st letter! THEY know this fact through John's letter, not through their faith!!! grammar grammar grammar! (and context).” Is there any truth at all to what this COC minister is claiming? Is he trying to add to salvation through faith? Also, I believe that genuine believers will persevere in their faith, but the COC minister said: “On a similar note, F. F. Bruce once wrote concerning the Perseverance of the Saints (the “P” in Calvin's TULIP, also known as “once saved always saved”) that, “Yes, the saints will persevere, but why must they be exhorted to do so?” (cf Rev 2-3; 1 Tim 2:15; Col 1:23; Acts 11:23; 14:22; etc.)” - Can you please answer his question above? Just a note, I'm not a 5 point Calvinist, but I really don't understand these passages above to teach that faith in Christ plus perseverance = salvation. I see perseverance as the result of our faith (cause and effect). Is there a difference between persevering “in the faith” and persevering “to keep our faith?”
The phrase that we need to investigate in 1 John 5:13 in order to answer your question is “have written.”
These things I have written to you who believe in the name of the Son of God, so that you may know that you have eternal life. (NASB) 1 John 5:13
This phrase comes from the Greek word GRAPHO. The word is in the aorist tense. This implies that John had written something at some point in time but we do not when. If John was referring to a letter that he had previously written, it is more likely that John would have used another tense, such as the Greek perfect tense That would have referred to something that had already been written in the past. But John did not do that. The aorist most likely refers to all of the words contained in the 96 verses that he had already written of 1 John. It is important to notice that he only wrote 8 more verses after verse 13. Why shouldn’t John’s statement refer to the 96 verses that recipients of his letter had just read?
Throughout the letter of 1 John, the apostle John gives us a list of tests that we can apply to ourselves to determine if we are truly followers of Jesus Christ. He actually gives us seventeen tests in this book. We would encourage you to read a previous question, “Will I go to heaven?” It provides the list of tests that are included in 1 John. You may also be interested in another series of tests at “Evidences You Are A Christian.”
Perseverance of the Saints
You are also correct that true Christians will persevere in their faith. That is the message of James 2:19,
You believe that God is one. You do well; the demons also believe, and shudder. (NASB) James 2:19
F. F. Bruce is also correct that the saints are exhorted to persevere. But the implication that the Church of Christ minister made is incorrect. May we encourage to read the study titled, “Saved Only Once.” It will address this issue.
True believers will act as believers and never leave the faith. They may stray for a period but they will eventually come back. That is, true believers will come back. They will persevere until the end. Yet, God calls us to walk as children of light. We are to act like believers. May the Lord bless you.
Reference Links:Will I go to heaven?
Evidences You Are A Christian.
Saved Only Once