It is verified in the heart of each individual believer by the Holy Spirit...Odd that you don't know that...
Plus, there are a few hundred prophecies in the OT about the NT times that have come to pass...Without error...No other book or religion can make that claim...Apparently you don't know that either...
But the only way you know the scriptures are the word of God is because your religion told you so...But they don't believe it either...Because their religious tradition over rides the scriptures...