John has been talking at length about the necessity of loving. He has said numerous times that if we don't love one another, we're not Christians. That love is the evidence of our salvation. In the first five verses of chapter five, he says that same thing again, but throws in some terminology that we probably need to understand a bit better...
John mentions a basic Bible concept here that a surprising number of Christians and even Bible teachers don't have a handle on. It is the concept of being "born of God," of being "children of God." So, let's take a few minutes to examine this.
To be a child of God, or a son of God, your Father must be God. Sounds simple, right? It is. In the lengthy genealogy of Luke 3, we see listed...
Luke 3:38 ...Adam, the son of God.
Adam was the son of God because his father was God. How?
Gen. 2:7 ...the LORD God formed man of dust from the ground, and breathed into his nostrils the breath of life; and man became a living being.
Who was Adam's father? God. That's why Adam was the son of God.
The angels are also called "sons of God." As when the Lord asked Job if he had been around at creation:
Job 38:4 "Where were you when I laid the foundation of the earth? Tell Me, if you have understanding
Job 38:6-7 ...Or who laid its cornerstone, when the morning stars sang together
And all the sons of God shouted for joy?"
Angels do not get married and have children (Matt. 22:30). They are called sons of God (Job 1:6; 2:1; Gen 6:2; 6:4) because each of them was created directly by God.
So, why does the Bible call Christians "children of God"? After all, our birth certificates have a man's name listed as our father, not God. Well, you don't have to be created by God to be a child of God. You can also be adopted.
The gospel of John tells us that when Jesus came into the world,
John 1:12-13 But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name, who were born, not of blood nor of the will of the flesh nor of the will of man, but of God.
Paul wrote,
Gal. 3:26 ...you are all sons of God through faith in Christ Jesus.
When we come to faith in Jesus Christ, we are born again (John 3:3; 1Pet. 1:3), new creations (2Cor. 5:17), adopted by God (Eph 1:5).
Rom. 8:15 ...you have received a spirit of adoption as sons by which we cry out, "Abba! Father!”
And so Adam the son of God wasn't born, he was created from the dust. The angels, the sons of God, weren't begotten, they were created. Christians are people who were conceived in sin (Psa. 51:5), but later born again to be adopted as children of God.
But Jesus is the ONLY begotten Son of God. He has existed from eternity:
John 1:1-3 In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things came into being through Him, and apart from Him nothing came into being that has come into being.
Jesus was not created, and He was not adopted. His Father has always been God. He is the only begotten Son of God because He was conceived in the womb of a virgin, and born as a human being, already being the Son of God. He...
John 1:14 ...became flesh, and dwelt among us, and we saw His glory, glory as of the only begotten from the Father, full of grace and truth.
John 3:16 "For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life."
This is what God is referring to when he says,
1John 5:1 Whoever believes that Jesus is the Christ is born of God...
1John 5:5 Who is the one who overcomes the world, but he who believes that Jesus is the Son of God?
John talks about testifying, which means "giving evidence or proof." Jesus said very plainly,
John 5:31 "If I alone testify about Myself, My testimony is not true."
If someone comes to you and says, "I'm the Son of God. I can forgive your sins, believe me," and no one else can back that up, then you shouldn't believe them. Jesus said, "If I'm the only one testifying about Me, then don't believe Me."
Of course, the miraculous works that Jesus did testified of Him (John 10:25). But John points out that God has also given His testimony of Jesus Christ. As a matter of fact, He's done it in three ways: the water, the blood, and the Spirit.
At the waters of His baptism, God testified of Jesus:
Matt. 3:16-17 After being baptized, Jesus came up immediately from the water; and behold, the heavens were opened, and he saw the Spirit of God descending as a dove and lighting on Him, and behold, a voice out of the heavens said, "This is My beloved Son, in whom I am well-pleased.”
At the blood of His cross, God testified of Jesus:
For three hours, darkness fell upon all the land (Matt. 27:45). The veil of the temple was torn in two (Matt. 27:51), an earthquake struck the city (Matt. 27:51), many who had died came to life and appeared to people in Jerusalem (Matt. 27:52-53).
And, most personal to each of us, the Spirit testifies of Jesus (Heb. 10:15; Acts 15:8). Jesus promised,
John 15:26 "When the Helper comes, whom I will send to you from the Father, that is the Spirit of truth who proceeds from the Father, He will testify about Me"
And Paul said,
Rom. 8:16 The Spirit Himself testifies with our spirit that we are children of God
We can try to convince people to believe, debating the issues, and reasoning with the facts. But the Spirit's testimony of the truth of Jesus Christ is the greatest of all.
When you believe, the Spirit of God stops being next to you and begins to live inside of you. The testimony is in you, and you no longer say, "I'm pretty sure," or "I'm becoming convinced." Instead, you can testify, "I know for a fact."
When someone doesn't believe in Jesus Christ, they are really saying, "God is a liar. I don't believe His testimony about Jesus."
What is that testimony? That those who have faith in Christ will have eternal life, while those who do not will be separated from Him forever.