Among Hebrews, everyone believed in the God Abraham (that is when the God's chosen people did not worship pagan gods on numerous occasions in their history).
The Jews of the OT beieved in the same God we believe, I would say.
Of righteous Jews there can be no doubt. The question I still struggle with on how to answer is what about the Jews of today? (I am talking about practicing Jews of the Jewish faith.) My inclination is to say "No", He cannot be the same God because of the denial of Christ. However, I've heard leaders whom I otherwise think are OK say that He is the same God. I'd welcome any opinions on how to answer this.