The Interpreting Word (1:1):

1:1 It may be that the name Joel is more than just the proper name of the prophet. In the Hebrew, “Joel” combines two words, Yah, which is an abbreviated form of Yahweh, the Hebrew name for the Lord, and ʾēl, which means god. Thus, the name “Joel” signifies “Yahweh is God,” and while many pious parents could have affirmed their faith by giving their son that name, “Joel” may also point to one of the major concerns of the book, namely, apostasy or the worship of false gods. Joel condemns Judah in the strongest terms for its sin, but he never says what that sin is. Yet, in the two climaxes of the book, in 2:27 and 3:17, the statement is, “Then you will know that I am . . . the LORD your God.” The implication is that Judah has not hitherto known. Rather, if the pro…