“He who has the Son has life; he who does not have the Son of God does not have life.”
The plain purpose of verse 12 is to make patent that eternal life comes from the Son of God. Christianity is more than acceptance of a proposition; it is the possession of Person of the Son. The individual united to the Son is united to eternal life. He who rejects the Son rejects eternal life itself.
He who has the Son has life;
This is a logical inference that if a person has the Son of God he has eternal life because it is impossible to have one without the other.
We see the Christian’s vital relationship with the Son by the word “has”. “Has” carries the idea of possession. The Christian currently has possession of eternal life in this life. The present tense in the Greek indicates that Christians continually possess eternal life.
John 3: 16 “For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life.”
Jn 5: 24 “Most assuredly, I say to you, he who hears My word and believes in Him who sent Me has everlasting life, and shall not come into judgment, but has passed from death into life.”
he who does not have the Son of God does not have life.
The flip side is negative – a person who does not “have the Son of God does not have life”. John directs this statement against the Gnostics who rejected Jesus Christ as the Son of God. Gnostics do not have and hold eternal life.
Eternal life comes exclusively from the Son of God at the moment of salvation.
Eternal life does not come from our merit; it is an unmerited gift. We find that gift solely in Jesus Christ. Eternal life comes exclusively through Him. The Christian receives eternal life as a present possession at the moment of salvation. We receive eternal life at the moment we receive Jesus Christ as Savior.
Jn. 3: 36 “He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him.”
Jehovah Witnesses do not “possess” eternal life because they reject Jesus Christ as the Son of God. We find eternal life solely by belief in the Son and His finished work on the cross.