I recently attended the baptism of a young lady who had given her heart to the Lord and wished to make that public confession, in accordance with the Word. Her testimony is that she was unsure before of her salvation, and she wanted to get right with God and really begin a new life with Him. It is a beautiful thing to know where you stand with God and to have that assurance.
John's first letter to the Church is overflowing with this matter of assurance. While he gives, as we've seen, various reasons for writing, it all culminates to this point – to make sure of our relationship with Christ. He runs through the issues of walking in light vs. darkness, loving the brothers, holding onto truth. It's a checklist for us to see how we're doing; and he brings it all together here in chapter 5 as he says quite plainly (in verse 12), “If you have the Son, you have life, and if you don't have the Son, you don't have life.”
I have heard the arguments of the skeptic and I have seen the ways of the world. But the only question left to ask at the end of the day is, What are we doing with Jesus Christ? because our answer to that question dictates whether or not we are truly living. And that's what John wants to know; more over, that's what he wants us to know! Do we believers, we the bride, know for sure where we are with the Son? There's far too much out there distracting us, and there's far too much at stake, for us to play around. We need to be certain, and living in that certainty.
He says, "The point of all this is to make sure you know you have unending life." It is beyond just feeling good or doing the right thing. It is having a peace that will hold you together through anything, and allowing that peace – that Spirit – to rule in your heart. It is the resolve of a martyr, whose faith is unshaken, even behind prison bars, even on the floor of the Roman Coliseum. As he is tied to the pyre, as he hangs on the cross, as he is beaten and mocked, he knows he has the Son and so he has life. He has unending life.