Overcomers (!) in verse 5 stand on the vital testimony of 1 John 5:6-12. That testimony refers to Jesus’ life and death.
Jesus’ baptism (coming by water, says John) was performed so that he might “fulfill all righteousness” (Matthew 3:15). This was the story of his life: perfect righteousness. He achieved what we never can, perfect righteousness in every action, thought, attitude, value, and belief, perfect keeping of the Ten Commandments. This qualified him to stand in our place as a man–not just as God the Son, but as a man with us. (See also John 1:1-18.)
As for his death, this too was crucial. Jesus Christ died in our place. He atoned for our sins and shame by assuming the position of death that we all deserve. Being sinless, he could not be destroyed by death, so he rose to life on the third day!
This is the testimony all “overcomers” (verse 5) must have. It is confirmed to us by the Holy Spirit, demonstrating that God, not just apostles, has stamped this testimony with approval. (For more on the Holy Spirit’s testimony, see John 3:6-8.)
Therefore, says John, eternal life only comes by holding this testimony to be true. Notice how John leaves no room for other religions. Without this testimony about the perfect life of Jesus and the atoning, substitionary death of Jesus, and the Holy Spirit’s confirmation in our lives, there is no eternal life. Further, any other testimony not in agreement with this calls God a liar, says John.
Application: It is time to evaluate all the testimonies you and I allow to influence our decisions. If you have not already, will you do more research into the life and death of Jesus Christ by reading John’s gospel?