Albert Barnes Commentary John 3:33

"He that hath received his witness hath set his seal to [this], that God is true." — John 3:33 (ASV)

He that has received his testimony. He has received and fully believed his doctrine. He has yielded his heart to its influence.

Has set to his seal. To seal an instrument is to make it sure; to acknowledge it as ours; to pledge our veracity that it is true and binding, as when a man seals a bond, a deed, or a will.

Believing a doctrine in the heart, therefore, is expressed by sealing it. By believing, we express our firm conviction that it is true and that God who has spoken it is true. We vouch for the veracity of God and assume as our own the proposition that it is the truth of God.

God is true. He is faithful; he is the author of the system of doctrines, and will fulfill all that he has promised. We learn here:

1. That to be a true believer is something more than to hold a mere speculative belief of the truth.
2. That to be a believer is to pledge ourselves for the truth, to seal it as our own, to adopt it, to choose it, and solemnly assent to it, as a man does in regard to an instrument of writing that is to convey his property or that is to dispose of it when he dies.
3. Every Christian is a witness for God, and it is his business to show by his life that he believes that God is true to his threats and to his promises (Isaiah 43:10).
4. It is a solemn act to become a Christian. It is a surrender of all to God, or giving away body, soul, and spirit to him, with a belief that he is true, and alone is able to save.
5. The man that does not do this—who is not willing to pledge his belief that God is true—sets to his seal that God is a liar and unworthy of confidence (1 John 5:10).