I have posted a number of times in the past about examples of henotheism in the Old Testament/Hebrew Bible. HERE is a post by Daniel McClellan in which he goes into a significant amount of detail on the topic. I am one who was trained in the manner of Wiggins who he cites in the post. In my reading, statements in Deutero-Isaiah have been taken as monotheistic; however, McClellan makes a good case for pushing the development of monotheism back a bit further and not taking statements in Deutero-Isaiah as strictly monotheistic. Check out his post and see what you think.