In the old days, the chief idol of Connacht, or possibly — as the old scribes believed — the whole of Ireland, was Crom-Crúach, who stood among twelve lesser idols on Mag Slecht, the Plain of Prostration, at the place that became Kilnavert when the Christians built a church there instead. Tradition has remembered Crom-Crúach as a serpent, a notion well suited to his name, which means something like »crooked-bloody«; the records make no mention of his appearance, but it may be that in actuality he was a bullet-shaped stone.
Crom-Crúach was a terrible, ravenous god; the manuscripts record that women used to tremble merely at passing the place where he stood nigh the road, and for good reason, for the tribute exacted by the idol was the lifeblood of every first-born child. It is no wonder then that the blessed Pádraig destroyed it, when in his travels he came to Connacht; what is more interesting is how. According to the Tripartite Life of St. Patrick,
[...] when the saint found that he could not convert the worshippers of the awful idol, he climbed a nearby hill, and stretched his arms to heaven in prayer; he raised the Bachall Isa, and when he gestured with it at the idol, it toppled over, the mark of the Bachall in it, though the staff had not even touched the idol, and the twelve subordinate idols were swallowed by the earth, up to their necks.
It is an excellent story, but also implausible; there is another version of it, however. This is how the Metrical Dindsenchas relates it:
Ever since Heremon was king, the idols were worshipped; but when the noble Pádraig of Macha came there, he plied a hammer upon the Crom, and he broke it apart, from top to bottom, and he drove the demon out: not little his skill.
This demonstrates the value of older sources, for here, in more senses than one, we see a saint we might believe in.