Hebrews 4:2 clarifies that they heard the gospel as it applied to them; it was good news. They would be freed from slavery and be taken to the land of their forefather Abraham, which would be given to them. When they heard this, all they had to do at this time was to give their mental assent that they believed. How much overcoming had they done? None. God had already set His mind He would save them, and all they had to do at this point was to agree.
What they heard was good news—it was fantastic good news—until Pharaoh turned up the heat ,and their joy of hearing the good news turned to affliction and persecution. This was part of God's purpose, too, because what they were experiencing—the combination of believing and then receiving a test—was beginning to show a difference between Israel and Egypt. A kind of sanctification, a setting apart, was taking place. In this part of the process, it was more difficult for the Israelites than it was for the Egyptians, and in the Israelites' estimation, it was greater than they could bear. This difference intensifies throughout the plagues.
John W. Ritenbaugh
Unleavened Bread and Pentecost