You shall have no other gods before me. Exodus 20:3
I am the way, and the truth, and the life. No one comes to the Father except through me. John 14:6
"This intolerant claim to exclusive worship is something unique in the history of religion, for in antiquity the cults [the various centers of worship] were on easy terms with one another and left devotees a free hand to ensure a blessing for themselves from other gods as well."
Gerhard von Rad, Old Testament Theology (New York, 1962), I:208.