When something is declared as "truth" in the Bible it means it comes from the Lord and is true down to the deepest levels of reality.

172. But even though the things that are seen in the heavens are largely similar to things on earth, they are not alike in essence. The things that exist in the heavens come from heaven's sun, while earthly things come from our world's sun. Things that arise from heaven's sun are called spiritual, while things that arise from our world's sun are called natural.