I John 5:12,13 “He that hath the Son hath life; and he that hath not the Son of God hath not life. These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God.”
One of the many clear passages of Scripture that deals with the topic of eternal security is found in the above two verses. People that want to add works to salvation tend to ignore these two verses.
They are plain, and it would take some real twisting of the clear words of God to make it say that you can lose your salvation. There are two keys to salvation found in these verses. The first is “the Son.” The second term is “believe.”
When you believe on the Lord Jesus Christ for salvation, you generally ask Him to forgive you and come into your heart and life to be your Savior and Lord (Boss). When you ask in faith – He comes in, according to Revelation 3:20: “Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him.” Once He comes into your heart and life, you “have the Son.”
Our text verse says that if you do not have the Son of God as your Savior, then you do not have eternal life. That is very simple. If you have the Son you have – not might have – you have (possess) eternal life.
After this, John restates the same principle a different way for those who missed it in the first verse. He goes on to say that once you have believed on Jesus Christ for salvation, “that ye may know that ye have eternal life.” Notice that he makes it a certainty – “ye have” – right now, you possess eternal life – and eternal life never ends.