IS THE OLD TESTAMENT GOD'S WORD?

In every age and generation there will be honest people who are looking for the true guidance. Allah (S.W.) had sent his messengers with signs, light, and true guidance. However, the previous books of Allah (S.W.) that revealed to prophets were lost due to the circumstances of writing and the way of  conservation, and they were subject to distortion and loss. Thus, people went astray from the guidance and the right path, and people used other books that attributed to Allah (S.W.). 

These books do not contain - except slightly - the true guidance and light. These written books contain and conclude the weakness of the human beings and their ignorance. They are full of contradictions, and issues, which no sane or wise person would accept their attribution to Allah (S.W.). This does not mean that these books are lack of the true guidance completely, but, as I mentioned, they were subject to alteration and human contradiction.