I'd like to know what religon, if any, did the current Muslims have before Mohammad came. Since they are sons of Ishmael, were they following Judaism?
Judaism is the following of the Law of Moses, which was given exclusively to the sons of Israel. "And Moses called all Israel, and said to them: "Hear, O Israel, the statutes and judgments which I speak in your hearing today, that you may learn them and be careful to observe them. The LORD our God made a covenant with us in Horeb. The LORD did not make this covenant with our fathers, but with us, those who are here today, all of us who are alive" (Deuteronomy 5:1-3).
Ishmael was a son of Abraham and half-brother of Isaac. Isaac had two sons: Esau and Jacob. It is Jacob who was also called Israel and it is his descendants who received the law of Moses. From Esau came the Edomites and from Ishmael came the Arabs.
Prior to rise of Islam in seventh century A.D., there was a wide mixture of religions among the Arabs. Many followed after various deities, such as Hubal, Wadd, Allat, Manat, and Uzza. The Ghassandi and Lakhmid tribes were predominately Christians. The Hymarites converted to Judaism in the fourth century.