Charles Ellicott 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.—Better, he that received. “Has set to his seal,” better, set his seal. It had been so. Earlier disciples, such as Andrew and John (John 1:40), had passed from the Forerunner to the Great Teacher, and had heard in His words that which spoke to the divine in their own spirits, and had come from the short first meeting with the conviction, “We have found the Messias.” They received the witness, and, as they heard it, they too became witnesses.

Just as a man sets his private seal—here, the reference is likely to the common Eastern stamp that affixed the name—and by it attests the truth of a document, so they attested, through the power that witness had over their lives, to their recognition of it as truth. It has always been so. The moral fitness of Christianity to meet the spiritual needs of men, and its moral power over the lives of men in all the varying circumstances of culture, race, and creed, has raised up in every age a holy army of witnesses, who have set their seal to its divine truth. (Compare for the thought of sealing, John 6:27; Romans 4:11; Romans 15:28; 1 Corinthians 9:2; and so forth.)