I think the article intended 'secular zealotry' to mean something more like 'nonreligious zealotry' - the zealots are secular, not that the zealots are zealous

I think the article intended 'secular zealotry' to mean something more like 'nonreligious zealotry' - the zealots are secular, not that the zealots are zealous about secularism. This is intended to contrast against the religious zealots referred to in the previous sentence.