Should we consider the passage that tells us the word is God is that what is actually the eternal unchanging word?
The phrases "unchanging word" and "God is the same yesterday and today and tomorrow" is a warm fuzzy for fundamentalists. Malachi 3:6 It Sounds good, but what does it mean really? If the Mosaic Law says one thing in the Old Testament and Christ objects to it in the New Testament...what does that mean? Does that mean the word changed? Does it mean God changed His mind? Does it mean God changed? Christ objected to the Mosaic Law concerning divorce, saying that Moses permitted them to divorce their wives. Well does that mean that the Ten Commandments and the rest of the Mosaic Laws were laws of men...not God? Did God change His mind?
Same thing goes for the Mosaic Law concerning eye for eye .... life for life, Christ objected to this and said, turn the other cheek....
People...fundamentalists do not like change, even in the Bible, much less after the biblical era. They would like to think everything concerning Christianity was nailed down in Bible. That is simply not true. We learned that slavery and polygamy was wrong, we learned that women should not be forced to marry someone. And some Christians are still in the process of learning that women are human too. Considering the urgency in the New Testament that Christ was going to return very very soon, there was not a focus on getting married or a focus on the family. The focus was saving souls in "those last days." Paul suggested and preferred celibacy and gave up marriage as a concession. That concept was followed by church administration for quite awhile. (The Catholics still do it.) But Christians as a whole understood that, that would not work...So Christian beliefs became very focused on the family.
Also as time went on Christianity learned that families were a stabilizing factor in society and religion and was very important.
God is real and Christianity is founded on the reality of God. There is no reason to come up with fantasy beliefs. Those types of beliefs are not going to make sense and will always be questioned. There is no reason to believe that God retired after the close of the Bible, no reason to believe He had nothing further to tell us. That does not mean that God changed, it means there were things He needed to tell us that they could not bear then....just as the scriptures say.
So back to the unchanging word...what does it mean? We can debate what the unchanging word means. But what it can't mean, is that God never changes His mind. I can give you a few examples in the Old Testament where the scriptures literally say He changed His mind or recanted. Things changed between the Old Testament and New Testament and some try to go back to the Old Testament and Christianize it. It does not work because the Jews are still around and that is their religion and they were custodians of the Old Word of God long before Christianity came along.