From the Greek name Ισιδωρος (Isidoros) which meant "gift of Isis", derived from the name of the Egyptian goddess Isis combined with Greek δωρον (doron) "gift". Saint Isidore of Seville was a 6th-century archbishop, historian and theologian.
Though it has never been popular in the English-speaking world among Christians, it has historically been a common name for Jews, who have used it as an Americanized form of names such as Isaac, Israel and Isaiah.