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)
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