Whoever has accepted it has certified that God is truthful.
Read John 3:33 Using Other Translations
He that hath received his testimony hath set to his seal that God is true.
Whoever receives his testimony sets his seal to this, that God is true.
Anyone who accepts his testimony can affirm that God is true.
Scripture quoted by permission. Quotations designated (NIV) are from THE HOLY BIBLE: NEW INTERNATIONAL VERSION®. NIV®. Copyright © 1973, 1978, 1984, 2011 by Biblica. All rights reserved worldwide.
(New International Version Bible Online)