He that hath received his testimony hath set to his seal that God is true. For he whom God hath sent speaketh the words of God: for God giveth not the Spirit by measure unto him. The Father loveth the Son, and hath given all things into his hand. He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.John 3:33-36
It is important to remember that belief is not the cause of eternal salvation; it is an effect and evidence of it. Having said that, we should not belittle the importance of the preaching of the gospel and the call for God’s people to believe it!
Without belief there is no strong assurance. Without belief there is no secure hope in our minds.
But a person who truly does believe that “God is true,” will have more peace, joy, and liberty in his earthly life.
This timely salvation found in the gospel assures the believer that what God says is true and that salvation was secured on the cross!
Consider what John later writes in his first general epistle. He states his purpose in writing the letter. He then defines that purpose. Finally, he concludes with the full definition of joy.
And these things write we unto you, that your joy may be full.1 John 1:4
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.1 John 5:13
John tells us that true joy is in knowing that we ARE the sons of God and HAVE eternal life! The true source of this confident joy is our belief that Jesus is the Son of God. This is the clearest evidence for our salvation and the seal of it until the Lord returns.