The Hellenic gods had already become discredited before Christianity really showed up in force. Educated people believed in different forms of Platonic and Pythagorean pantheism, which emphasized a divine, transcendent Oneness as the source of natural law and the human soul. So the Hellenic gods ended up either being seen as different forms or incarnations of this Oneness, or just made into purely literary figures, or treated as a cynical show for the lower classes. They were already less-than-real by the time Christianity showed up.

The Abrahamic god fit into this because it could be identified with that pantheistic sense of divinity, while giving people something 'tangible' that they could worship, an emotional experience. There was a niche for that kind of belief, and the other gods of nature just didn't fit into the way people were approaching religion at the time.

EDIT: This is really standard stuff that anyone would learn from an introductory text on Western philosophy and religion. There isn't any real controversy over this. If you're going to downvote, you should probably explain how exactly I'm wrong, though I suspect it's just people assuming the church saved humanity from "idolatry"