God's Words

Why is that, when God writes something, such as the ten commandments he etched in the stone tablets, it is clear, concise, and unambiguous, such as "Thou shall not steal," but, when men write something that "God told them," it is symbolic, wordy, ambiguous, and open to many different interpretations? If God has something to say, why does he not just write it himself and eliminate the "sinful" middle men.