“God’s word”

I have a question for any theists who have ever used the phrase “God’s word” in a serious sentence (and, I mean, come on, we all know that’s pretty much all of you):

How do you know what is or isn’t “God’s word”?

Do you think that the Shrimad Bhagavad Gita is God’s word?
Do you think that the Tanakh is God’s word?
Do you think that the NT is God’s word?
Do you think that the Qur’an is God’s word?
Perhaps you think that God’s word is to be found within the Joseph Smith papers…

Tell us all, please: which scriptures, exactly (which version of which holy book) do you think is (or which do you think are) closest to “God’s word”?
But most importantly, please, because this is the main thrust of this OP: HOW have you come to that conclusion?