الآية رقم (67) - مَا كَانَ إِبْرَاهِيمُ يَهُودِيًّا وَلاَ نَصْرَانِيًّا وَلَكِن كَانَ حَنِيفًا مُّسْلِمًا وَمَا كَانَ مِنَ الْمُشْرِكِينَ

(67) - (Abraham was neither a Jew nor a Christian, but he was one inclining toward truth, a Muslim [submitting to Allah]. And he was not of the polytheists.)

This is a confirmation that Abraham (PBUH) has been neither Jewish nor Christian since both Judaism and Christianity were revealed after him.

Abraham (PBUH) used to incline from polytheism towards monotheism