But skeptic says: I don't know how many times the OT claims to be God's inspired word, but such claims can't authenticate that it’s indeed any God-inspired word.
The claims don't prove anything.
Besides, other religions have sacred texts claiming to be a god’s word, too. For example:
The Quran says its Islamic text was taught by a God
The Merciful 55:1 It is the Merciful [Allah] who has taught the Koran.
The ancient Bhagavad Gita (The Song of the Lord) says most of its Hindu text is the word of Lord Krishna, a God
Bhagavad Gita 2.1 Krishna, spoke the following words ...
The ancient Zend Avesta says its Persian text is the word of a God, too
Vendidad, Fargard 1:1 Ahura Mazda [God] spoke unto Spitama Zarathushtra [the prophet], saying ...
Recap: The Bible might say it's God word a lot of times, but it's only lying a lot of times.