In my opinion, the second most important book of the Bible is 1 John, and for this reason: it is the only book of the Bible that claims that it was written so that those who believe in the name of the Son of God may know that they have eternal life (1 Jn. 5:13). You say that you believe that Jesus is the Christ, the Son of God? My question for you is this: how do you know that you believe that Jesus is the Christ, the Son of God? Have you ever stopped to consider what it means to believe something? Some might say it means to have an intellectual assent to it, but what does that mean? The definition that I have come up with is this: to believe something is true is to live as if that thing is true. I don’t think that there is any better way to put it. How do you know that you believe something? You find out if you are living as if that thing is true. So it is with believing that Jesus is the Christ. How do you know that you believe that He is the Christ? You find out if you are living as if He is the Christ.
In 1 John, the Holy Spirit puts those who claim to believe that Jesus is the Christ to the test. The first test is the test of knowledge: do you actually know some of God’s Word? God’s Word says that we are conceived as evil people, and thus, do evil things. Do you know that? Furthermore, God has revealed who He is to us. Do you know that? In addition, God’s Word says that Jesus is both God and a man, that He died to pay God for people’s evil deeds, and that He came back to life. Do you know that? Are you trusting only in Jesus, His death, and bodily resurrection from the dead for salvation from the punishment you deserve from God?
The second main test in 1 John is the lifestyle test. 1 John basically says this: if you actually have eternal life, then you are going to live as if you are fit to live with God forever. The book challenges us to ask some questions like: are you living a life of obedience to God’s commands in His Word? Are you laying down you life for other Christians? Are you acknowledging the sins that you know you commit, and agreeing with God that they are evil, damnable, and disgusting acts that you ought not to commit? Do you love to obey God? If these things are true of you, then you can know with certainty that you believe that Jesus is the Christ, and that you will live forever with Him.
In conclusion, I would challenge you, if you have read the gospel of John, to read 1 John before you go on to another book of the Bible. Not only does 1 John provide us with an opportunity to find out if we will live forever, but it also helps us to apply the knowledge that we will live forever to our lives. It encourages us to continue believing that Jesus is the Christ, to obey Him, to purify ourselves, to overcome the world, to love our brothers and sisters in Christ, and to be devoted to prayer, among other things.
Do not go a second without knowing from God’s Word that you will live forever. It is better to find out that you don’t have eternal life, and come to gain it through believing that Jesus is the Christ, then to live without true certainty, and come to find out you don’t have it when you are sentenced to hell, to suffer incomprehensible agony forever.