Full Idea
It is very difficult to find a single monotheistic statement in the whole of the Pentateuch, and even the Ten Commandments take the existence of other gods for granted ("There shall be no strange gods for you before my face").
Clarification
The Pentateuch is the first five books of the Bible
Gist of Idea
There is virtually no sign of monotheism in the Pentateuch
Source
Karen Armstrong (A History of God [1993], Ch.1)
Book Reference
Armstrong,Karen: 'A History of God' [Mandarin 1993], p.31
A Reaction
The transition from polytheism to monotheism is very strange. First God is 'jealous' of other gods, then supremely above them, and eventually totally exclusive. It's like watching the rise of Stalin.