What is the secret mark that infallibly identifies a child of God? It would be vain presumption to decide this based on our own judgment. But God's Word reveals it to us, and where we have revelation as our guide, we can walk with certainty.

Here is what Scripture tells us about our Lord: "To all who received him, to those who believed in his name, he gave the right to become children of God." So then, if I have received Christ Jesus into my heart, I am a child of God. That same verse describes this receiving as believing on the name of Jesus Christ. If I believe on his name—if I simply trust myself, from the heart, to the crucified but now exalted Redeemer—then I am a member of the family of the Most High. Whatever else I may lack, if I have this, I have the privilege of being God's child.

Jesus puts it another way: "My sheep listen to my voice; I know them, and they follow me." Here is the heart of the matter. Christ reveals himself as a shepherd to his own sheep, not to others. The moment he appears, his own sheep recognize him. They trust him. They are ready to follow him. He knows them, and they know him. There is mutual recognition, constant connection.

So the one mark, the sure mark, the infallible mark of being born again and adopted into God's family is a hearty faith in the appointed Redeemer.

Reader, are you in doubt? Are you uncertain whether you bear this secret mark of God's children? Then do not let another hour pass without praying, "Search me, O God, and know my heart."

Do not trifle here, I adjure you! If you must play games with something, let it be about secondary matters. Your health, if you will. The deed to your house. But about your soul? Your never-dying soul and its eternal destiny? I beseech you to be in earnest. Make certain work for eternity.