[pinkpanther]

Good morning.

That verse came from the Jewish book of Deuteronomy. They are indeed monotheists. They don't believe there are three gods. They discourage their followers from going near a church because they believe Christians are polytheists.

Early jews in the early centuries believe in 2 persons being God..

Where in the OT can I find that they believe that the Christians are polytheists? 

the OT only lays the groundwork for understanding God's nature and the Trinity doctrine emerged later in the NT