The word is "monolatry" and the concept itself is new to me.
The early Israelites were not monotheists, they were monolatrists. They didn't believe there is only one deity - they believed there were many but they were required to only worship their Guy. As my instructor analogized, it wasn't that they thought there weren't other gods out there, but this was the only one they were allowed to marry.
This has been a Fun Fact to Know and Tell.