If I did not possess an assurance that Jesus Christ rose from the dead, I would not even be a Christian. I would do what every other person would do, who is intelligent enough to recognize the futility of existence in this temporal world: being born only to die and having to suffer in between. I would make the most of the what I have without having to suffer, if possible. People who have demonstrated that God does not exist, do not waste their time telling everybody, they make the effort to enjoy every carnal pleasure possible before they die—because this is what all animals do.
For those who are interested in discovering the truth, it just so happens, actual historical evidence of Moses’ existence has been discovered. This is besides the fact that Moses’ existence is recorded in numerous writings from antiquity. For there is also archaeological evidence that proves the existence of the Israelites in Egypt and that the Exodus led by Moses, as recorded in the Bible, did actually occur.
As is postulated within the idea at the root of the question you ask, Judaism had to originate from someone. The fact that Israelites observed the Sabbath Day as an ordinance to commemorate the nations deliverance from Egypt testifies of the truth of Moses' existence and the reason the nation exists.
- You shall remember that you were a servant in the land of Egypt, and Yahweh your God brought you out of there by a mighty hand and by an outstretched arm. Therefore Yahweh your God commanded you to keep the Sabbath day. (Deuteronomy 5:15)
The Truths Found in The Ten Commandments Are Evidence That Moses Existed