Abraham wasn't a Jew.
Judaism, Christianity, and Islam are sometimes referred to as the "Abrahamic religions", because of the role Abraham plays in their holy books and beliefs. In the Hebrew Bible and the Qur'an, Abraham is described as a patriarch blessed by God (the Jewish people called him "Father Abraham"), and promised great things, father of the People of Israel through his son Isaac; the Muslims regard Ishmael as the father of the Arabs. In Islam, Abraham is considered to be one of the most important of the many prophets sent by God. In Christian belief, Abraham is a model of faith, and his intention to obey God by offering up Isaac is seen as a foreshadowing of God's offering of his son, Jesus. In Islamic belief, Abraham obeyed God by offering up Ishmael.
His original name was Abram (אַבְרָם "High/Exalted father/leader", Standard Hebrew Avram, Tiberian Hebrew ʾAḇrām); he was the foremost of the Biblical patriarchs. Later in life he went by the name Abraham. There is no contemporary mention of his life, and no source earlier than Genesis mentions him. He probably lived between 2166 BC and 1991 BC. According to the Jewish tradition, Abraham was born 1,948 years after creation and lived for 175 years, which would correspond to a life spanning from 1812 BCE to 1637 BCE.
but who's counting