Elijah comes from Hebrew and is traditionally translated as "my God is Yahweh," a name carried by a prophet known for uncompromising conviction. It's commonly read as suggesting devotion held firmly rather than loosely -- a name associated with steadiness of belief more than outward display.
Mercury in the sixth house of a nativity, the native shall change from one religion to another, & will have his felicity in part impedited by reason of his inconstancy. - William Lilly (1602.-1681.)