Treasury of Scripture Knowledge
He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
The person who believes in the Son has never ending life, but the person who disobeys the Son will not see life [i.e., will not experience never ending life], but [instead], God's wrath remains on him.
"Truly, truly, I tell you, the person who listens to my message and believes [in] the One who sent me [i.e., God] has never ending life [i.e., as a hope. See Titus 1:2; 3:7]. He will not be judged [and condemned], but has [already] passed from being [spiritually] dead to being [spiritually] alive.
And this is what [else] my Father wants: That every person who sees the Son [i.e., with the eye of faith] and believes in Him should have never ending life, and I will raise him up [from the dead] on the last day."
But these [signs] are written down so that you will believe that Jesus is the Christ, the Son of God, and that when you believe [this], you will have [never ending] life in His name [i.e., through His person and work].
So, since we are made right with God by [our] faith, we have peace with Him through our Lord Jesus Christ.
Therefore, none of those who are in [fellowship with] Christ Jesus will be condemned.
1 John 5:12
The person who has the Son [in his heart] possesses this "life;" the one who does not have the Son of God does not possess this "life."
He that believeth not
The person who believes [i.e., the Gospel] and is immersed will be saved [i.e., from condemnation], but whoever does not believe it will be condemned.
how will we escape [punishment] if we neglect such a great salvation? [For it was] first announced [to people] by the Lord and then confirmed to us [i.e., the writer and other Christians] by those who heard Him [i.e., the original apostles].
Pay careful attention so that you do not refuse [to hear] God when He speaks to you. [See verse 9]. For if those people [i.e., the Israelites] did not escape [judgment] when they refused [to hear] Him who warned them on earth [i.e., God speaking through Moses at Mount Sinai], how much less [likely] will we escape [judgment] if we reject Him who warns from heaven [i.e., Christ]?
1 John 5:10
The person who [sincerely] believes in God's Son has the evidence [of it] within his heart, [confirming God's testimony]. The person who does not believe God [i.e., what He says about Jesus], accuses Him of lying, because he has not accepted the [irrefutable] testimony of God concerning [the identity and mission of] His Son.
[The world will be proven guilty] of sin for not believing in me.
For we conclude that a person is made right with God by faith [in Christ], apart from [obedience to] the requirements of a law [or, the law of Moses, See verse 20].
And [so] we see that they were not able to enter [a state of rest with God] because of [their] unbelief.