He started out as a darling of the religious right, because he played a major role in causes the religious right considered "theirs." When he began to write with equal clarity about how other aspects of the religious right's focus are at odds with those same deeply held principles that led him to do the work the right loved, they turned on him like this.
Complex moral issues are exactly that, complex. We need more intelligent people thinking hard about them, not more polarization into "you're either with us or against us" mindsets.
I'll be clear here that I'm not interested in judgements on literature provided by someone who frames their worldview as hating one of the few writers willing to address the real complexities of real issues today.