Islam. Christianity fundamentally redifined monotheism with the concept of Jesus's divinity.
the New Testament is monotheistic
Christians are the only ones that believe that. Other religions regard the Trinity as a rejection of monotheism. Just letting you know.
I am well aware of the confusion and it is NOT caused by the New Testament, rather it is caused by people's extrapolation (the Trinity Doctrine)
Judaism believed God is omnipresent and that the Holy Spirit is God's Spirit...so there is no discrepancy in the New Testament stating that the one and only God was manifested in the flesh while at the same time being omnipresent.
The only thing that confuses Jews and Muslims into thinking Christianity is not monotheistic is the confusion caused by some people's interpretation of the Trinity Doctrine. If the New Testament is allowed to speak for itself, without extrapolation, then there would be no confusion.
The New Testament states that the ENTIRE GODHEAD dwelt in the body of Jesus Christ, therefore what was in Jesus Christ was not part of the godhead, rather it was the whole enchilada.
Col 2:9 "For in him dwelleth all the fulness of the Godhead bodily."
And there is no discrepancy in God himself coming down to redeem Israel, for it is written: "He himself will redeem Israel from all their sins." Psa 130:8