How do we know if we have truly experienced the spiritual reality of new birth? How do I know if God has acted on my life? This is such a critical question in our lives, and John Piper addressed it in a 2007 Christmas sermon, of all places. We pick up with John Piper citing 1 John 5:12:
“Whoever has the Son has life; whoever does not have the Son of God does not have life.”
John 1:14, 16, “The Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. And from his fullness we have all received grace upon grace.” That is where our life comes from. The Son, the Word made flesh is our life. This is the testimony.
How do you know that you are a child of God? Well, how do I know that John Piper is alive? Is it my birth certificate? Does anybody believe you are alive because you have on file a birth certificate? You don’t. It is because you breathe.
It is exactly the same with Jesus Christ. You know that you are a child of God because you breathe. You are alive. You see him for who he is. You love him for who he is. You trust him for who he is. You embrace him for who he is. That is how you know you are alive. The testimony is within you. And what is it again — the testimony? First John 5:11, “And this is the testimony, that God gave us eternal life.” That is how you know. You are alive to him — alive to God — and dying to sin.
The aim of the new birth is to awaken faith in the crucified, incarnate Son of God. And if there were no incarnate, crucified Son of God, then the new birth would not be performed, because the point of it would not be possible. The incarnation of the Son of God is necessary because the life that we have in the new birth in union with him is the life of the Son, the incarnate Christ.
I come now to close with justification and purification. Or, if you want to use the old sanctification, you can. But purity is what you use in this text. I am going to use it. First John 3:4–5, “And everyone who makes a practice of sinning also practices lawlessness; sin is lawlessness. You know that he appeared in order to take away sins, and in him there is no sin.”
John says: If you have experienced the new birth and, thus, your heart has been awakened to hope in Jesus Christ and you cannot wait until he appears, because all your sin will be done away with and you won’t be battling on the Internet anymore and you won’t be battling with pride anymore and you won’t be battling with selfishness anymore and you won’t be battling with all the bitterness and anger in your life, then you will be free and like him — if that is the passion of your life. 1 John 3:2–5 says it plainly: If the passion of your life is to be purified from all sin in the presence of Christ in the future, you are only kidding yourself — if you don’t want purity to happen in your life right now. “He is going to show up some day, and then I will really want to be pure.”
I used to play those games when I was a kid. “I’ll get saved when I am old, because it is boring to be saved. So get saved when you are old.” No. It won’t happen. The hardness will creep over you and you will lose all your capacity to know him, see him, love him — and God will withdraw from you and you will perish, thinking that on your death bed you could repent. And you will be an Esau pleading for repentance and it will not be given. Don’t play that game. If you are 30 years old, don’t play it. If you are 40, don’t play it. 50, don’t play it. And sure don’t play it if you are 60. Don’t play that game.
We will purify ourselves, meaning, we are going to fight. Nobody in this room is perfect. Nobody will be perfectly pure before you die. The question is: Who is fighting? Who is fighting? Who says, “Yes, I want Jesus to come back”? “I want to be like him perfectly. It grieves me not to be more like him than I am. I am going to fight sin now.” Who says that? That’s the children of God talking. I don’t care how many times you fall down, if you get up talking like that, you are a child of God.