Sure, humanism can get it right. But how do we know when it gets it right? And when it's wrong the rest of the time, does that even matter?
And whether we see it manifest is a contextual sidebar that doesn't change the absolute moral Truth. I'm not looking for manifestation, I'm looking for answers about the Truth. One perfectly good and Christian man has one answer, and another perfectly good and Christian man has another answer. If I'm seeking God's Truth, how do I find it, or is your contention that we never, ever see it manifest?