John Piper, God’s Great Mercy and Our New Birth:
How Do You Know You Were Born Physically?
Let me get at this with a provocative question: If I asked you, “How do you know that you were born from your mother’s womb?” what would you answer? You would answer, “I’m alive! I exist outside my mother’s womb. I’m here.” And that’s right. And that is all the answer needed.
You would not answer, “I know I was born because I’ve got a birth certificate at home.” Or, “I know I was born because I did some historical research at a hospital in Chattanooga, Tennessee, and found a document with a little footprint on it that matches the curly lines on the bottom of my foot.” Or, “I collected signed affidavits of three or four witnesses that saw my mother pregnant and soon after saw me in her arms.”
You would simply say, “I know I was born because I am alive.”
How Do You Know You Were Born Spiritually?
But now suppose I asked an average evangelical churchgoer today, “How do you know you were born again?” How many would answer, “Because I am alive to God. I have a living hope. I have a living faith. I once had no spiritual life and now I am alive spiritually, with spiritual appetites and spiritual enjoyments. Once I was dead and now I am alive in God. I know him, I love him, I trust him. I hope in him. I follow him. The proof that I was born again is my life today!”
How many, rather, would answer, “I know I was born again because I did what you must do to be born again: I asked Jesus into my heart; I prayed to receive Christ; I walked down an aisle and accepted Jesus; I have a card here in my wallet that I signed on June 6, 1952, where I pledged that Jesus is my Lord.”