I'm reading Edwards again these days and also thinking about zeal in the thought of the apostle Paul, specifically in Romans 10:2. It was fun to read this today and see the two come together. And it's another good statement of the kind of thing I would like to promote through this site.
Holy affections are not heat without light; but evermore arise from the information of the understanding, some spiritual instruction that the mind receives, some light or actual knowledge. The child of God is graciously affected, because he sees and understands something more of divine things than he did before, more of God or Christ, and of the glorious things exhibited in the gospel; he has some clearer and better view than he had before, when he was not affected: either he receives some understanding of divine things that is new to him; or has his former knowledge renewed after the view was decayed: Rom. 10:2, “They have a zeal of God, but not according to knowledge.”
--Jonathan Edwards, Religious Affections, Part 3, Sign #4