The point, for Christians, isn’t the amassing of ‘scientific’ claims upon which to base their decisions (concerning Gay Marriage or anything else). The point for Christians is to hear as clearly as possible the testimony of Scripture and to adjust our lives to it rather than it to our lives.
Bob is a great guy and I don’t think anyone who knows either of us doesn’t realize how close we are. But we have different perspectives PRECISELY because I see life through the lens of Christian faith and he does not.
It is for this reason that our views on several issues differ. I don’t think Bob a bad person for it, nor do I like him any less. I simply recognize that, at the end of the day, we approach problems and issues from differing starting points.
Until Bob becomes a Christian or I become a secularist (neither of which are likely) we shall continue to disagree. But that’s ok. At least, for me.