Were the Israelites in Goshen sinless, and how could sinners still be safe?
No, the Israelites in Goshen were not sinless; they were sinners just like everyone else. Their safety did not rest on their own goodness or anything they had earned, but on the blood applied to their doors by faith. Under that blood they were totally secure; without it they would have lost their firstborn.
Les teaches that the Israelites in Goshen had nothing to worry about or fear. They were absolutely secure, not because of anything they had earned, not because of their goodness, but because of one thing: the blood on the door. That was an act of faith. If they had scoffed and refused to put the blood on the door, they would not have been safe and would have lost their firstborn. Scripture gives no indication that any Jews were lost; evidently every single Jewish household in Goshen had the blood on the door and were safe. Les qualifies that being under the blood does not give license to sin, but the blood applied made them totally safe and secure even though they were sinners just like we are. He connects this to the New Testament teaching that those under the blood are safe and secure, and says the whole exodus from Egypt was God's redemption of the nation.