Why do Jewish rabbis consider Christians pagan?
Jewish rabbis regard Christians as almost pagan because Christians worship the triune God—Father, Son, and Holy Spirit—while the rabbis do not recognize the Trinity in the Old Testament. They conclude Christians worship three gods rather than one, since the Old Testament's revelation of the triune God is vague to them.
Les explains that the Hebrews and rabbis, even in the present day, call Christians almost pagan because they think Christians worship three gods. The issue is the Trinity: the Old Testament is vague about it and does not clearly reveal it, so they do not recognize the Trinity back there. Les notes the Old Testament has evidences of the triune God, but the full revelation that God is Father, Son, and Holy Spirit is part of the mystery Paul brings out. Because they still do not see the Trinity in the Old Testament, they charge Christians with worshipping three rather than one God.