When the Bible speaks of eternal life, it refers to a gift of God that comes only “through Jesus Christ our Lord” (Romans 6:23). This gift is in contrast to the “death” that is the natural result of sin. However, the Bible inextricably links eternal life with the Person of Jesus Christ. John 17:3 is an important passage in this regard, as Jesus prays, “Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent.” Here, Jesus equates “eternal life” with a knowledge of God and of the Son. There is no knowledge of God without the Son, for it is through the Son that the Father reveals Himself to the elect (John 17:6; 14:9).
This life-giving knowledge of the Father and the Son is a true, personal knowledge, not just an academic awareness. There will be some on Judgment Day who had claimed to be followers of Christ but never really had a relationship with Him. To those false professors, Jesus will say, “I never knew you. Away from me, you evildoers!” (Matthew 7:23). The apostle Paul made it his goal to know the Lord, and he linked that knowledge to resurrection from the dead: “I want to know Christ—yes, to know the power of his resurrection and participation in his sufferings, becoming like him in his death, and so, somehow, attaining to the resurrection from the dead” (Philippians 3:10–11).
How can you know that you have eternal life? First of all, confess your sin before our holy God. Then accept God’s provision of a Savior on your behalf. “Everyone who calls on the name of the Lord will be saved” (Romans 10:13). Jesus Christ, the Son of God, died for your sins, and He rose again the third day. Believe this good news; trust the Lord Jesus as your Savior, and you will be saved (Acts 16:31; Romans 10:9 –10).
John puts it so simply: “God has given us eternal life, and this life is in his Son. Whoever has the Son has life; whoever does not have the Son of God does not have life” (1 John 5:11–12).
(Excerpts from Got Questions mobile app entitled ”What is eternal life”)